92 i)f?' Pimnett, On the alleged influence of lecithin 



On the alleged influence of lecithin upon the determination of 

 sex in rabbits. By R. C. Punnett, M.A., Gonville and Caius 

 College. 



[Bead 22 February 1909.] 



In 1907, Professor Russo, of Catania, published an account of 

 certain experiments* in which he claimed to have brought about 

 a great increase in the relative number of female young produced 

 by rabbits. The method consisted in the injection of lecithin 

 either subcutaneously or into the abdominal cavity. In the paper 

 referred to Russo gives particulars of 100 litters from injected 

 does as well as of another 100 litters in which the does were not 

 injected. The injected does produced 217 (^(^ and 431 ? ?, 

 as against 400 </</ and 287 $ $ from those not treated, and the 

 author consequently claims to have raised the proportion of 

 females from 41'8 °/^ to 56'5 % o^ the total offspring. 



Such remarkable results have naturally attracted attention 

 and several criticisms have recently appeared. It has been pointed 

 outf that the statistics published by the author are not complete, 

 but that, as he himself states, only those litters from the animals 

 treated with lecithin were recorded in which the number of females 

 preponderated over that of males (cf. Russo, loc. cit. p. 367, foot- 

 note). Until the complete statistics are available, any conclusions 

 as to the effect of lecithin upon the proportions of the sexes must 

 necessarily be of doubtful value. 



On other grounds Russo's results have been recently criticised 

 by Heape|. Russo claimed to have distinguished histologically 

 between the ovarian ova destined to produce females and those 

 destined to give rise to males. According to him fatty matter is 

 present in the former though not in the latter, and he supposed 

 that the injection of lecithin resulted in a higher proportion of 

 ova containing fat, i.e. of female ova. Heape points out that there 

 are good grounds for regarding Russo's male ova as ova which are 

 in some stage of degeneration and consequently not destined to 

 give rise to embryos of either sex. 



* Atti Acad. Lincei, 1907, Serie 5 a. Vol. vi. pp. 313—384. 

 t Bateson and Punnett, Science, N.S., May 15, 1908. 

 + Proc. Camh. Phil. Soc, Vol. xiv. p. 609. 



