.Some Pointa in the Sjiermatofjenesis of Mammalia. 1 Ho 



stituents exist togethei", and we aie brought back a|?ain U) the question 

 with which we started. — „What is the function of the cytoplasmic 

 constituent?" 



The only answer to be found, in fact the only answer which 

 seems intelligible, is that it acts as an hereditary leaven, in the some 

 way as the nuclear constituents are supposed to opei-ate in producing 

 an hereditary balance during fertilisation. But we may go a little 

 further. If the chromatin theoretically requires a „Reductions-Teilung" 

 in order that its constituents may be previously got into an appro- 

 priate condition of number and quantity, ought not the essential 

 constituents of the cytoplasm to be treated in a similar fashion? 

 There is the archoplasmic metamorphosis. Can this represent such a 

 phenomenon? I am unaware of anything equivalent to it in ovogenesis, 

 and this cytoplasmic reduction would thus appear to be a purely one- 

 sided aifair. 



However this may be, the existence of a differentiated cyto- 

 plasmic constituent in the mammalian spermatozoon, where it might 

 least have been expected, points strongly to the conclusion that it 

 will be found eventually to exist in that of other animals. 



In concluding I must thank the Department for the free use of 

 the Huxley Research Laboratory and Prof. Howes for his kindness 

 and advise while I was there. 



Description of plates VII and Till, 



Refereiice letters. 



a Archoplasm. a s Archosome. b c Chromatic body, c Centrosome. e c Cer- 

 cosome. c h Extra nuclear chromatic particle, n c' Nucleolus. 



Unless otherwise stated, all the figures applj' to the spermatids of rat. 

 Figs. 1 — 11. Stages in the primary and secondary division. 

 Figs. 12—14. Formation of the chromatic body. 

 Fig. 15. Contiguous cells showing centrosomes and cercosomes. 

 Figs. 16 — 21. Formation of archosomes. 



Fig. 23. Spermatid of dog, with chromatic body, first stages of archoplasmic 

 metamorphosis and centrosomes. 



