MancJiester Memoirs, Vol. I. (1906), No. 0. 5 



original syntelosome they contain sixteen chromosomes. 

 Giglio-Tos (38) has pointed out that these observations 

 of Petrunkewitsch are discordant with those of Meves (64), 

 who has attacked the problem from the other end by 

 studying the spermatogenesis of the drone bee. Un- 

 fortunately Meves' description and figures of the chromo- 

 somes are not clear enough to permit me to come to a 

 definite opinion, and I do not think that they can be of use 

 in either contradicting or supporting Petrunkewitsch's 

 observations.* 



The somatic cells are formed from the female 

 pronucleus. As this only contains half the somatic 

 number of chromosomes, Petrunkewitsch suggests that the 

 normal number is formed by a subsequent mitotic division 

 without a separation of the halved chromosomes. 



Tenthredinid/E. 



Many species of saw-flies lay eggs which develop 

 parthenogenetically. Taschenberg (93) gives a list of the 

 species in which parthenogenesis is found. Two forms 

 occur — Homoparthenogenesisand Heteroparthenogenesis, 

 and there may be thelyotoky, arrhenotoky or deutero- 

 toky. As a general rule the females are much more 

 numerous than the males. It has also been found that 

 the parthenogenetic young are constitutionally weak and 

 may die before attaining maturity. As either or both 

 sexes may be produced, this constitutional weakness 



* Meves (64) finds that the primary spermatocyte contains 16 chromo- 

 somes. It gives off a small anucleate bud which he considers to be a 

 rudimentary spermatocyte. The large secondary spermatocyte then divides, 

 forming a small spermatid which he describes as abortive ; the large residual 

 spermatid forming a single spermatozoon. The author does not state whether 

 there is any reduction in the number of chromosomes in the last division, and 

 his figures are not clear enough to enable me to judge. 



