No. 485] 



THE DETERMINATION OF SEX 



313 



and females would be obtained bv such a random choice. Instead 

 of the theoretical distribution of 1000 males and 1000 females, 

 the actual numbers of males and females in 2000 births are 1017.6 

 and 982.4 respectively, or, for convenience in calculation, 1018 

 males and 982 females. The probability that, in choosing at 

 random, we should obtain such a distribution is .60984 X 10"^"°. 

 The probabihty that in eleven siuh choices, we would alwavs 

 obtain the same (Iistiil.ini..n is infinitesimal. The probabihty 

 that, in every case where \\\v l.iiihs are numerous enough to be 

 representative of the actual eondiiions, we siiould alwavs obtain 

 practically the same distribution is ])raetieally zero. There is 

 about the same probability that Mendel's law UMs for all these 



A single concrete example taken from organic cheniistrv will 

 serve to emphasize this point and perhaps to make this mathemati- 

 cal abstraction clearer. In the transformation of aeetaldehvdc to 

 lactic acid by the addidon of hydrocyanic acid, saponification and 

 oxidation, each of two isomeric forms of lactic acid is, on the 

 theory of probability, equally likely to be jyrodnced. 'J'he two 

 forms differ in optical activity, one being dextro-rotatory and the 

 other laevo-rotatory. Kx])eriinenlally, it is found that the two 

 forms are actually ])roduced in exactly e(|ual amounts, and the 

 mixture of the two is o|.tically inactive. A variation of from 

 three to seven per cent from the theoretical yield w(.uld he fatal 

 to the theory of probability. In u'eneral. in the synthesis of organic 

 bodies in which two isomeric forms are in.ssif)|e ;ind tlieoreticaliv 

 equally probable, the experimental results agree much more <'loselv 

 with the theory than do the statistical results of hmnan })irths. 



Neither ovum nor spermatozoon play asexual roles. — It is evi- 



