JACQUES LOEB 543 



"The diploid number, as well as the similarity in form of the tetrads of the 

 parthenogenetic and normal animals, may have been brought about by the reten- 

 tion of the second polar body, or by a premature division of the chromosomes 

 without the division of the cell body just before the first cleavage." 



Brachet* had previously counted the number of chromosomes in a 

 parthenogenetic tadpole, 18 days old, and found a diploid number, 

 but, of course, it was out of the question to ascertain the sex of the 

 tadpole. 



In my last pubHcation on the subject I mentioned the possibihty 

 that the parthenogenetic females might have the haploid number of 

 chromosomes. This question can only be decided by an actual count 

 of the chromosomes in female parthenogenetic frogs. It is perhaps 

 of interest in this connection that Hovasse^ in an investigation of 

 the number of chromosomes of young parthenogenetic tadpoles of 

 frogs reports to have found both the diploid number and the haploid 

 number. Since it is not possible to determine the sex of early tad- 

 poles the observations of Hovasse do not answer the question whether 

 or not the female parthenogenetic frog possesses a haploid number of 

 chromosomes. There is, however, no doubt left that some if not all 

 of the parthenogenetic male frogs possess a diploid number of chro- 

 mosomes. 



We usually received in one shipment a large number of female 

 frogs either from South Carolina or from Chicago as soon as the 

 spawning season began. It took about half a day to puncture the eggs 

 of one female frog and as a consequence some time elapsed before the 

 eggs of every female in the lot were punctured. It was found that 

 tadpoles of good vitality were obtained only from the eggs of the 

 first and second frogs used for the experiment. The eggs of the frogs 

 which were punctured later, after the frogs had been in the labora- 

 tory for 2 days or more, either gave no tadpoles at all or if tadpoles 

 were produced they died in less than 3 weeks, while the tadpoles from 

 the eggs punctured immediately after the arrival of the frogs went on 

 developing although the conditions under which the eggs were kept 

 were the same in all cases (see Table I). 



^Brachet, A., Arch. Biol, 1911, xxvi, 362. 



^Hovasse, R., Compi. rend. Acad. Sc, 1920, clxx, 1211. 



