The authors prove some approximate formulas for the computation of the mean and the standard error of quotients of two variates, correlated or uncorrelated, with not too high coefficient of variation. The formulas obtained are subsequently applied to some date on mensuration of horses of the Brazilian breed Mangalarga, by the eclectic system of LESBRE. The relsults obtained directly by the actual computation of the quotients as well as by means of the formulas with the aid of statistics of the numerators and the denominators are given in table 3, showing excellent agreement.

The present work deals with the study of the effects of selfing and crossing in pures lines of okra inbred for five generations and the methods of breeding in this plant. This work is party of a large program of this Dept. to study heterosis in plants naturally self pollinated. The technic of selfing consists of tying with a string the floral bud before anthesis. To make controlled crosses, it is necessary to emasculate the flowers removing the anthers with small forceps, and to cover the flowers with a bag and wait for 1 or 2 days until the blooming. Also, the male parents are covered with paper bags prior to flowering. Finally, the pollen is brushed lightly over the stigma of the emasculated flowers and the females unit rebagged. The authors have tried without sucess the technic of soda fountain straw used for cotton. The treatments were: I) Fl of the cross pure-line x foreign variety (not improved by breeding). II) Fl of the cross pure-line x parental variety and III) pure-line 5 generations inbred. In order to compare the production of these three treatments, a randomized blocks with 4 replications was designed; since we had 6 families in each treatment, the total number was: 4 replications x 3 treatments x 6 families: = 72. Each familiy was planted in lines of 10 plants. Owing to the design devised, the present experiment corresponds to a split-plot. The analysis of variance of the number and the weight of the pods is given in tables 2 and 4, and shows the following: 1) The production expressed in both numbers and weights of the cross, - pure lines x foreign variety - was statistically smaller than the others treatments, i, e., the cross of pure-lines x parental variety and the pure-lines; 2) The production of the treatments pure-lines x parental variety and selfed purelines was the same. It was proved that the selfing do not produce harmful effects in okra, it was benefical, since after 5 inbred generations the production was the same when compared with Fl of the parental variety. Also, the methods of pure-lines are indicated to improve varieties of okra.

Êste trabalho faz parte do estudo do melhoramento genético das mirtáceas frutíferas, que vem sendo realizado pela Seção de Frutas Tropicais do Instituto Agronômiso e pela Seção de Genética da Escola Superior de Agricultura "Luiz de Queiroz", em Piracicaba. Colaboraram na parte analítica a Seção Técnica "Química Agrícola" e a Cadeira de Química, da "Luiz de Queiroz''. A extração de vitamina C foi feita num liqüidificador durante dois minutos, utilizando-se o ácido oxálico a quatro por mil como solução protetora. A determinação se fez no "EEL. portable colorimeter". A determinação do conteúdo de vitamina C no fruto integral de plantas expostas ao pleno sol revelou o seguinte : planta 1, 2147 mg/100 g ; planta 2, 2389 mg/100 g ; planta 3, 2322 mg/100 g de fruto (vêr figura 1-A). Os teores de ácido ascórbico encontrados nos graus de maturação foram : fruto verde, 2716 mg/100 g ; fruto de vez, 2391 mg/100 g; fruto maduro, 2417 mg/100 g. O fruto verde tem o teor mais alto, enquanto o de vez e o maduro não diferem entre si. Também foram analisadas as diversas partes do fruto maduro, encontrando-se na casca 2482 mg/100 g e na polpa 3018 mg/100 g. Isto quer dizer que na "cabeludinha" a riqueza em ácido ascórbico aumenta da periferia para o centro. Tal fato é de suma importância, uma vez que só é aproveitada a polpa, portanto, a parte mais rica do fruto. Determinou-se também o conteúdo de vitamina C no fruto integral e maduro, de plantas sombreadas, encontrando-se na planta 1, 717, 28 mg/100 g; na planta 2, 838,66 mg/100 g ; na planta 3, 560,83 mg/100 g ; na planta 4, 713, 28 mg/100 g. Êstes resultados indicam, provavelmente, que as plantas localizadas à sombra são bem mais pobres em ácido ascórbico que aquelas crescendo ao sol; indicam ainda, que entre as plantas sombreadas há diferenças significativas, talvez de origem genética. As figuras dos gráficos 3 e 4 mostram, respectivamente, que a "cabeludinha" é a fonte mais rica de vitamina C entre as mirtáceas nacionais e de tôdas as frutas brasileiras. Comparando-se a "cabeludinha" com outras frutas exóticas, ricas em ácido ascórbico, nota-se que somente a cereja das Antilhas (Malpighia spp.) lhe leva vantagem.

The studies on the vitamin C content in fruits of Myrciaria glomerata Berg, reported in this paper were complementary to the breeding work on fruit plantas of Myrtacex, carried out cooperatively by the Seção de Frutas Tropicais, Instituto Agronômico, Campinas, and Seção de Genética, E.S.A. "Luiz de Queiroz", Piracicaba. The ascorbic acid content was determined in the blend obtained by running the pitted fruits in a blendor for 2 minutes in presence of a 0.4 per cent oxalic acid protecting solution. The quantitative determinations were made with an EEL portable colorimeter. The total vitamin C content in fresh fruits from trees exposed to full sunlight were as follows (in mg/100 g) : tree n.° 1, 2,417 ; tree n.° 2, 2,389 ; tree n.° 3, 2,322. Assays made with fruits at different stages of maturity gave the following results : green fruits, 2,716 ; full developed fruits, 2,391 ; ripe fruits, 2,417. Green fruits had thus a higher vitamin C content than either partially or completely ripe fruits ; the difference between the last two types was not significant. Different parts of the fruit that were assayed separately had the following vitamin C content (mg/100 g) : peel, 2,482 ; pulp (without seed), 3,018. The pulp which is the edible part of the fruit is thus richer than the peel. Vitamin C determinations in ripe fresh fruits from four shaded trees gave the following results (mg/100 g) : tree n.° 1, 717.28 ; tree n.° 2, 838.66 ; tree n.° 3, 560.83 ; tree n.° 4, 713.38. Fruits produced on shaded trees are therefore poorer in ascorbic acid than those from trees exposed to full sunlight. The variations between trees in the shaded group may be ascribed to genetic origin. Myrciaria glomerata fruits have the highest vitamin C content found among edibln fruits of Myrtacex (see table 3) ; it is also one of the tropical fruits richest in this vitamin, ranking third to the cynorrodum of will roses and fruits of Malpighia spp.

This paper deals with the variation of the ascorbic acid content in Natal orange as related to the type of rootstock and to the picking time. The determinations were carried out in the juice of fruits which had practically the same ratio total solids/acidity being selected only the highest values of such quotient. The results can be summaryzed as follows: 1. The rootstock has a significant influence on the vitamin C content of the scion; this influence shows two interesting aspects: first, the ascorbic acid contet itself varies as a function of the rootstock; among the three rootstocks studied the highest values were obtained on scion growing on Serra d'água orange; the lowest values were found in "limão rugoso" and "limão francês" was intermediate; the second point to be emphasyzed is the manner of variation of the ascorbic acid content in the different rootstocks: in the case of Serra d'água. the content decreases slowly whereas in "limão francês" the level remains nearly constant and suddenly falls down; finally in the case of "limão rugoso" the amount of ascorbic acid increases significantly to return to the primitive level. 2. The amount of ascorbic acid, not considering the rootstock influence, varies strongly as a function of harvesting time; for this reason the present factor must be borne in mind when sampling for the determination of ascorbic acid in orange is concerned.

This paper is a joined publication of the Depts. of Genetics and of Technology, of the E. S. A. "Luiz de Queiroz", Universidade de São Paulo, and deals with the variation of the percentage oil content in the whole seeds, the embryos and the seed-coat of 28 varieties of castor-beans (Ricinus communis, L.). Primarily, the authors, as a justification of this paper, make reference to the applications which castor-oil has in industry, medicine, etc. In accordance with the weight of 100 seeds, the varieties of castor-beans were classified into 3 classes : small seeds (100 seeds less than 30 g), medium seeds (100 seeds between 30 g and 60) and large seeds (100 seeds more than 60 g). The percentage of oil in the seed, embryo and seed-coat, the dimensions of the seeds and the weight of 100 seeds are given for every variety in table 1. In order to obtain an estimate of the variability for the methods of determination of the oil percentage, in the 3 differents parts of the seeds and also in the 3 groups of seeds, the coefficient of variability was calculate (table 2). It is showed that the variation in the seed and embryo is low and that in the seed-coat is very high. The analysis of variance, with regard to the difference among the 3 types of seeds (small, medium and large), among the 3 parts of the seed (whole seed, embryo and seed-coat) and residual error, is given in table 3. Only, the oil content of whole seeds among types of seeds was significant at the 5% level. The t test among the correspondent means is not significant for the difference between medium and large seeds is significant between both these types (medium and large) and small seeds. The fiducial limits in relation to the mean of the oil percentage in the 3 differents types of seed, show that there is one variety (n. 1013-2), which has a percentage of oil, in the medium type of seed, significantly at the 5% level (table 4), higher than the general mean. Since the distribution of the percentage of oil in the seedcoat is discontinuous, 5 groups were established (table 5). All the differences between groups are significant (table 6). For practical purposes, when we have to remove the seed coat, one should eliminate those varieties which loose at least 3% of oil by this procedure. There is a significant linear correlation at 5% level between the percentage of oil in the seed and in the embryo, of the smali and medium type of seeds (table 7), and also, when taking the 3 types together (lower part of table 7), one finds that the same is true. Also, the correlation between the percentages of oil in the embryo and in the seed-coat of the 3 types together is significant at 5% level. According to the results obtained in relation to the percentage in 28 varieties studied, it can be recommended, for breeding purposes, to work only with those varieties which belong to the medium and the large types of seeds.

In the present paper the authors deal with the content of ascorbic acid in guavas (Psidium guajava L.) and the methods of sampling used. Ascorbic acid was determined directly in the photoeletric colorimeter (EEL), after extraction with a 4 per cent solution of oxalic acid. Guavas from various parts of State of S.Paulo were used and the general mean found was around 100 mgm of ascorbic acid per 100 gm fresh weight of the material used for extraction. It was found that there is great variation in the ascorbic acid content according to the condition of the fruit: Ascorbic acid Condition content in Mean mgm/100 gm Green and hard 93,36 - 119,54 102,43 Small green 57,34 - 92,30 83,40 Firm ripe 71,28 - 115,98 90,32 Overripe 63,22 - 85,98 77,36 Of the diferent parts of the fruit, the skin has the highest content; the pulp between the skin and the parts containing the seeds, the "inner pulp" contains little and finallw the central parts, formed by the pulp between seeds, the "inter pulp" a engligible amount. The proportion of ascorbic acid found in the skin, inner pulp and inter pulp may be as high as 1.6: 1: 0. Furthermore, the section near the peduncule and the sepals are richer than equatorial crossections. It was proved that the amount and intensity of sun-light is at least one important factant factor determining differences in the ascorbic acid content of the fruit, which is higer in the parts which have received more light. A sharp decrease was found in the vitamin C content of ripe fruite stored in a home refrigerator. The periods of the preservation were 12-24-48-96 hours and the decrease of the ascorbic acid content m per cent was 23.4 - 42.0 - 66.8 - 76.4 of the initial content of 144.28 mgm/100 gm. The following five different methods of sampling in the determination of the amount of vitamin C were tested, with extraction in a Waring blendor: 1) whole fruit; 2,) sample taken form fruits cut into many small pieces; 3) half of a fruit divided by a crossection at equal distance from both ends; 4) half of fruit divided lenghtwise; 5) a transversal slice of about 1 cm. It was found that the two first methods geve the most reliable results.

1 - This paper is a joined publication of the Dept. of Genetics, Escola Superior de Agricultura "Luiz de Queiroz", University of São Paulo, and Secção de Citricultura e Frutas Tropicais, Instituto Agronômico, de Campinas, and deal with the number of seed per fruit and the polyembryony in Citrus, with special reference to the pummelos (C. grandis). 2 - For C. pectinifera, hibrid limon x acid lime, C. histrix and Citrus sp. the mean of seeds per fruit is 5,8 - 17,3 - 30,2 -94,6; for 14 pummelos the average was 100 and the range of variation 11 to 185 seeds per fruit. For the four above mentioned Citrus the cotyledons were classified into 3 types: big (near 8 mm.), medium (near 6 mm) and small (near 4 mm) and for the pummelos there was only one size of cotyledons, about 10 mm (table 1). 3 - The polyembryony was determined by two processes: a) counting of the embryos in the mature seed; b) counting after germination in flats or seed-beds. The rasults obtained are in table 2; the process a gave larger results than process b.The following pummelos are monoembryonics: melancia, inerme, Kaune Paune, sunshine, vermelha, Singapura, periforme, Zamboa, doce, Indochina, Lau-Tau, Shantenyau and Siamesa. Sometime it was found a branching of the main stem that gave a impression of polyembryonic seeds. 4 - It was shown by the x2 test that the distribution of embryo numbers fits the Poisson's series (table 2) in both processes. 5 - It is discussed in table 2 the variability of polyembryony for the following cases: a) between plants, within years. The teste for the differences of mean of polyembryony between 3 plants of C. pectinifera is statistically significant in 1948 and 1949; b) between yields of the same plant, within year. The same case of C. pectinifera may be used for this purpose; c) between process, within year. It is shown in table 3, for C. pectinifera and the hibrid "limon x acid lime" that there is a statistically signicicant between both process above mentioned.

The studies on polyembryony in Citrus reported in this paper show that there is a great variability in the degree of polyembryony among the seeds, fruits and trees of a same form or variety of Citrus. Seeds from different crops of the same plant also show considerable variation in the degree of polyembryony. In order to obtain reliable data on the degree of polyembryony in Citrus the samples for study should include a great number of seeds taken from several fruits of different trees. Since there is a yearly variation on the degree of polyembryony it was found necessary to study samples from several crops. The average number of embryos was determined by direct examination of individual seeds. Determinations based on the number of plants developed from every seed always give lower results as many embryos do not grow into seedlings.

1) O caráter presença de espinhos nos frutos da mamoneira é determinado por um par de fatores dominantes SS, sendo a forma recessiva ss, inerme. A interação alélica nao é bem intermediária, havendo uma predominância do fator S. Êste resultado foi anteriormente constatado por HARLAND (7), PEAT (8), DOMINGO (2), GURGEL (4) e FERNANDES (3). 2) A constatação da segregação 1 SS : 2 Ss : 1 ss foi feita após extensivas contagens de espinhos, tanto na forma paternal, como também no Fl, F2 e "back-cross". Por essas contagens foi verificado que existem variedades com números diferentes de espinhos, podendo-se distinguir dois tipos: variedades que têm muitos espinhos, com uma média aproximada de 170 espinhos por fruto e variedades que têm um número médio de espinhos, com uma média aproximada de 113 espinhos por fruto. 3) Embora a segregação dos fatores S e s seja monofatorial, todavia foi constadada por uma análise estatística detalhada, a presença de gens modificadores agindo na geração F2, introduzidos pelos tipos paternais. Assim, o segregante SS no F2, tem mais espinhos do que o pai homozigoto da mesma constituição. 4) Foram encontrados dois novos gens cal e ca2, com interação não alélica do tipo de polimeria complementar duplo-recessiva, dando no F2 uma segregação de 15 com espinhos uniformes : 1 com espinho careca, no "back-cross" uma segregação de 3 com espinhos uniformes : 1 com espinho careca. Estes gens determinaram, nos frutos com espinhos, a formação de zonas sem espinhos, ou como denominamos, "carecas". Estes novos fatores foram encontrados numa única variedade, de n.° 51, conhecida por laciniada, em virtude da for- ma especial de suas fôlhas. Esta variedade é de côr verde, apresenta cera na haste e possui numerosos cachos, porém pequenos. Ê tida como planta ornamental e foi originalmente importada de Erfurt, Alemanha. 5) Mesmo nas variedades inermes foi constatada a presença dos gens Cal e Ca2, para distribuição uniforme de espinhos, embora nas ditas variedades não se possa identificar a sua presença, em virtude do gen s ser epistático recessivo sobre Cal e Ca2. 6) Uma vez que os fatores S e CalCa2 sao independentes, isto é, possivelmente situados em cromosômios diferentes, fazendo-se o cruzamento de variedades com espinho careca x variedades sem espinho, obtem-se o PI com número de espinhos intermediário e distribuição uniforme. No F2 obtém-se a segregação de 45 com espinho uniforme : 3 com espinho careca : 16 sem espinho e no "back-cross" a segregação de 3 com espinho uniforme : 1 com espinho careca : 4 sem espinho.

1) In a former paper (4), the segregations of spiny versus spineless fruits was described as caused by one pair of mendelian factors, but in view of the possible pratical importance of spineless fruits a more detailed study was thought desirable. We may distinguish three main types of the distribuition of spine among the different varieties in our collections: Spineles fruits (inerms), found in a number of varieties. "Bald" fruits (a type called "careca" or bald owing to the irregular distribuition of the spines, which were always absent in some parts of the fruits while otrer patches might contain spines. Spiny fruits which may be classified into two or more groups, according to the number of regularly distributed spines. 2) The cross (spineless fruits) x (fruits with regularly distributed spines) HARLAND (7), PEAT (9) e FERNANDES (3) observed a 1:2:1 segregations in F2 while GURGEL (4) and DOMINGO (2) find it difficult to distinguish the homozygous and heterozygous spiny types without counting the number of spines. Such counts and the results of a detailed statistical analysis are now given. They show that the results of the 1:2:1 segregations are somewhat modified by both phenotypic modifications of the number of spines. The latter are caused by modifier genes introduced by both parents. 3) The cross between plants with a regular and an irregular distribuition of spines showed that the latter condition is due to the presence of two recessive complementary factors. Thus we have in F2, 15 regular to 1 irregular or partially "bald", and in back-crosses segregations in acordance with the ratio 3:1. 4) The cross spineless x "Careca", gave, as might be expected a trifatorial segregation in accordance with the following formula. "Inermes" "Careca" P : ss CalCal Ca2Ca2 x SS ca1ca1 ca2ca2 Fl : Ss CalCal Ca2Ca2 (with regularly distributed spines) F2 : 45 S- Cal- Ca2- (spines regularly distributed). 3 S- calca1 ca2ca2 ,"Careca) 16 ss ("inermes").

The general properties of POISSON distributions and their relations to the binomial distribuitions are discussed. Two methods of statistical analysis are dealt with in detail: X2-test. In order to carry out the X2-test, the mean frequency and the theoretical frequencies for all classes are calculated. Than the observed and the calculated frequencies are compared, using the well nown formula: f(obs) - f(esp) 2; i(esp). When the expected frequencies are small, one must not forget that the value of X2 may only be calculated, if the expected frequencies are biger than 5. If smaller values should occur, the frequencies of neighboroughing classes must ge pooled. As a second test reintroduced by BRIEGER, consists in comparing the observed and expected error standard of the series. The observed error is calculated by the general formula: δ + Σ f . VK n-1 where n represents the number of cases. The theoretical error of a POISSON series with mean frequency m is always ± Vm. These two values may be compared either by dividing the observed by the theoretical error and using BRIEGER's tables for # or by dividing the respective variances and using SNEDECOR's tables for F. The degree of freedom for the observed error is one less the number of cases studied, and that of the theoretical error is always infinite. In carrying out these tests, one important point must never be overlloked. The values for the first class, even if no concrete cases of the type were observed, must always be zero, an dthe value of the subsequent classes must be 1, 2, 3, etc.. This is easily seen in some of the classical experiments. For instance in BORKEWITZ example of accidents in Prussian armee corps, the classes are: no, one, two, etc., accidents. When counting the frequency of bacteria, these values are: no, one, two, etc., bacteria or cultures of bacteria. Ins studies of plant diseases equally the frequencies are : no, one, two, etc., plants deseased. Howewer more complicated cases may occur. For instance, when analising the degree of polyembriony, frequently the case of "no polyembryony" corresponds to the occurrence of one embryo per each seed. Thus the classes are not: no, one, etc., embryo per seed, but they are: no additional embryo, one additional embryo, etc., per seed with at least one embryo. Another interestin case was found by BRIEGER in genetic studies on the number os rows in maize. Here the minimum number is of course not: no rows, but: no additional beyond eight rows. The next class is not: nine rows, but: 10 rows, since the row number varies always in pairs of rows. Thus the value of successive classes are: no additional pair of rows beyond 8, one additional pair (or 10 rows), two additional pairs (or 12 rows) etc.. The application of the methods is finally shown on the hand of three examples : the number of seeds per fruit in the oranges M Natal" and "Coco" and in "Calamondin". As shown in the text and the tables, the agreement with a POISSON series is very satisfactory in the first two cases. In the third case BRIEGER's error test indicated a significant reduction of variability, and the X2 test showed that there were two many fruits with 4 or 5 seeds and too few with more or with less seeds. Howewer the fact that no fruit was found without seed, may be taken to indicate that in Calamondin fruits are not fully parthenocarpic and may develop only with one seed at the least. Thus a new analysis was carried out, on another class basis. As value for the first class the following value was accepted: no additional seed beyond the indispensable minimum number of one seed, and for the later classes the values were: one, two, etc., additional seeds. Using this new basis for all calculations, a complete agreement of the observed and expected frequencies, of the correspondig POISSON series was obtained, thus proving that our hypothesis of the impossibility of obtaining fruits without any seed was correct for Calamondin while the other two oranges were completely parthenocarpic and fruits without seeds did occur.

The occurrence of polyembryonic seeds in Mangifera indica has been known for a long time, but nothing is known with reference to the forms cultivated in Brazil. It was found impossible to count the number of embryos in the seed, in spite of the size of both seed and embryo. But the cotyledons are in such a way twisted around each other that it is impossible to separate them. Thus it was necessary to take into acount only the embryos which were able to germinate and their number was determined after 3 and 7 months. It was necessary to dig up the seedlings and wash off all soil in order to distinguish ramifications of shoot and root from the actual polyembryony. In 7 months old seedlings a new complication arises owing to the complete fusion of their base. Evidently there is a pronounced variation in the occurrence of polyembryonic seeds. In 30 resp. 40 germinated seeds, taken from one tree each oí the varieties "Santa Alexandrina" and "Itamaracá", all had one embryo only, while in "Pêssego" (one tree), "J. F. da Silva" (two trees) and "Oliveira Neto" (one tree) from 46 to 84% of the seeds contained more than one embryo. "Oliveira Neto", with 24 polyembryonic seeds out of the 25 germinated, had 4 seeds with four embryos and 1 with five.

The preliminary work with vegetables was described and special reference was-made to the group Brassica oleracea. a) Plants flowering easily in Piracicaba and probably in the whole State of São Paulo. To this group belongs the lettuce, endive, chichory, carrot, radish, kale, brocoli and cauliflower. b) Plants where special treatment is necessary for flowering, as cabbage. c) Plants that did not flower up to this moment, as Svisschard beet and beet. Three main factors contribute for the seedless condition in the group cabbage : lack of flowering, anormalities of the flowers and self-sterility. The preliminary experiments in controling these factors seem to indicate the possibility of seed production in this group. The systematics of the two species Brassica oleracea (Europe) and Brassica juncea (Oriental Asia) was discussed. The economical differences in the group Brassica oleracea are controled by Mendelian factors with complicate types of interaction. It is not necessary to look for special places in the State of São Paulo for vegetable experiments but the possibility of better results in the future, with appropriate conditions, is emphasized.

1 - The present paper deals with the results of studies on pollen fertility, number of seeds per fruit and frequency of polyembryony in Citrus. 2 - The pollen may be divided into four groups of which the first consists of the living and functional grains, colouring deeply with carmín acetic, germinating in sugar solutions fairly well. The remainny three types : half filled grains, empty grains, and small deformed grains are all inviable. 3 - The grains are generally spherical, 15 to 40ix in diameter. The smallest grains were found in Citrus hystrix and Citrus mitis (fig. 3 and 4), while citron and the grape-fruits have the largest grains (fig. 1, 2 and 5). 4 - Size and form are reasonably constant, except the hybrid "Citran-gequat", "limão galego" without spines, orange "Ruby" (fig. 6 to 8). 5 - Percentages of viable pollen grains are given in quadros IV to X. Tahiti Lime, probably a triploid, is completely sterile. "Baía" orange (Washington Navel orange) is completely male sterile, while the fruits of it may have some seeds. The two seedless varieties of "lima" and "pera" have 37,1 and 9,3% of viable pollen respectively. Regarding pollen viability oranges are the most variable. They show from 0 to 90% of good pollen (quadros IV and V). In lemons and limes the percentages vary from 50% and 80% (quadros VI to VIII). Tangerines, with exception of Satsuma owari, have generally more than 60% of good pollen. The grape-fruits, except the case of "Marsh-seedless", are characterized by a relative high pollen fertility. 6 - There is a certain variation of pollen fertility due to the external conditions. It seems to exist also a certain effect of the rootstock, on viability of pollen grains, as shown for the rootstock of "sour orange" and "rough lemon". 7 - The number of seeds per fruit was also determined and is given in the respective quadros (IV-X). 8 - There does not exist any consistent difference between open pollinated and selfed flowers in regard to the number of seeds per fruit (quadro XII). In 26 cross pollinations (quadro XIII), 6 caused an increase, 11 a decrease in the number of seeds. Especially interesting in this respect was "Baía" orange (Washington Navel), where, for instance, the cross pollination with the orange "Barão" gave in average 7 seeds per fruit, while in the cross with "Hamlim" the seed number was only 2,75 per fruit, this difference being highly significant. 9 - It is a well known fact that nucellar embryony is quite common in Citrus. The frequency of polyembryony has been determined for a large number of types. Even if an embryo is formed, we may not be certain whether it is produced by an adventicious growth of the nucellus or from a normally fertilized egg, as shown for instance for Citrus mitis x Poncirus trifoliata. (Fig. 15 and 16). Both twin embryos may be apogamous or one only, the other being in this case an hybrid. 10 - There exists a slight positive correlation between number of seeds and percentage of good pollen, with r = -f- 0,53. It should not be forgotten that the individual variations for these characters are very high, with coefficients of 93,01% for seed number and 33,18% for the percentage of viable pollen grains. Furthermore the variation of the forms is decidedly asymetrical owing to the pressure of the 0 limit. The general situation is best illustrated by the graph 1. With 0 to 10 seeds per fruit, there is no ordely variation of the percentage of good pollen. If the number of seeds rises between 10 and 20 seeds, the percentage of viable pollen grains rises generally above 50%, and if the number of seeds is still higher, the percentage surpasses 70%.

1 - The object of the present paper is the study of the effect of different rootstocks on pollen fertility of the scion. The material was obtained from experiments by Moreira (18), in progress at the Experimental Station, Limeira, São Paulo, and from experiments by Vasconcelos (1), in progress in the Experimental Orchard at Piracicaba, São Paulo. Homogeneity test of method 2 -A preliminary homogeneity test was carried out and showed that the methods for collecting and counting pollen were sufficiently satisfactory. This test consisted in the following : pollen was collected from 3 plants for each of 5 different rootstocks, budded with laranja pera and for each plant 3 determinations were made. The decomposition of the total error showed no significant, large component (quadro I). Both error and means per plant or rootstock gave no signs of heterogeneity (quadros II and III). Finally the error of a binomial distribution around a mean of 40,19% and with an average of 145 pollen grains per determinat