38 



BIOLOGIC BASIS OF SEX 



with an effect of each X only about 1/13 

 that of the Y and in the direction of female- 

 ness, the autosomes have one tenth the effect 

 of the X chromosomes but they too have 

 a composite effect toward femaleness. It is 

 to be remembered that the Y chromosome 

 variation is limited to 2 chromosomes 

 whereas the X chromosomes may total 4, 

 and the autosomes may range from 22 up 

 to 42, so that the total effect of the auto- 

 somes is definitely more than their single 

 effects. These data are for aneuploids. Ex- 

 amining Westergaard's data for 1953 for the 

 euploids and assigning the value of 1.5 for 

 the type observed when there was one Y 

 chromosome, four X, and four sets of auto- 

 somes, we have the following equation: 



Sex value = -1.29 Y + 0.10 X - 0.01 



(autosome sets) + 2.53 



In these data, as distinct from those above, 

 the autosomes are treated as sets of auto- 

 somes since they are direct multiples of each 

 other so the value of the individual auto- 

 some is but 1/11 that given in the equation. 



This equation shows no pronounced dif- 

 ference from that when the aneuploids were 

 utilized. The Y chromosomes have slightly 

 less effect toward the male side. The X 

 chromosomes have practically identical ef- 

 fects but there has been a shift in direction 

 of the autosomal effects on sex, although 

 the value is small. The constants are sub- 

 ject to fairly large variations arising 

 through chance. 



In Table 10 of Westergaard's 1948 paper 

 he presented data on the chromosome con- 

 stitution and sex in the aneuploids which 

 carried a Y chromosome. These data are of 

 particular interest as the plants are counted 

 for the i)roi)ortions of those which are male 

 to those which are hermaphroditic. The 

 plants with a Y chromosome plus an X are 

 all males. Those which have either one, two 

 or three Y chi'omosomes balanced by two 

 X chromosomes have 89 per cent males. 

 The plants with three X chromosomes and 

 one oi- two Y's have 36 p(T cent males and 

 those which have one or two ^■ chroiiiosoincs 

 and four X chromosomes have no males. 

 The woik iiiv()l\-cd in getting these data is, 

 of course, large indeed and is definitely 

 handicapped by the diiiicuHies in obtaining 



certain types. Thus the XXYYY and the 

 4X + 2Y types depend only on one plant. 

 There are eight observations but the fitting 

 of the data for the X and Y constitutions 

 eliminates three degrees of freedom from 

 that number so that statistically the obser- 

 vations are few. The data do have the ad- 

 vantage that the sex differences can be 

 measured on an independent quantitative 

 scale. The equation coming from the results 

 is: 



Percentage of males = 13.2 Y - 36.4 X 



+ 134.4 



These results show that the Y chromosome 

 increases the proportion of males and the 

 X chromosome increases the proportion of 

 intersexes. The data are not comparable 

 with those analyzed earlier as these data 

 are describing simply the ratio between the 

 males and intersexes, instead of the rela- 

 tions betw'een the males, intersexes, and fe- 

 males. The equation fits the observations 

 rather well, as indicated by the fact that 

 the correlation between the X's and Y's 

 and the percentages of males is 0.98, but 

 there are large uncertainties. 



As a contrast to these data we have those 

 presented by Warmke (1946) in his Tables 

 2 and 3. These data give the numbers of X 

 and Y chromosomes found within the plants 

 but not the numbers of autosomes, the auto- 

 somes being considered as 2, 3, and 4 gen- 

 omes. Analyzing these data in the same 

 manner as those of Westergaard's Table 1, 

 we find that the 



Sex type = -1.05 Y + 0.22 X -0.04 A 



-f2.25 



As indicated for Westergaard's data, the A 

 effect is now in terms of the diploid type 

 e(iualing 2, the trijiloid 3, and the tetra- 

 l)loid 4. 



The Y chromosome has a i)ronounccd ef- 

 fect toward maleness, the effect l)eing some- 

 W'hat less in Warmke's data than that of 

 Westergaard's. The X chromosomes on the 

 other hand, have nearly twice the female 

 infhience in Warmke's data that they do in 

 the phiiits grown by Westergaartl. A differ- 

 ence in sign exists for the effect of the A 

 rhi'oinosnnie genom(\s as well as a difference 

 in [\\v (|uantitati\'e effect. Th(^ values for 



