Some Points in the Spermatogenesis of Mammalia. 155 



the elongating nucleus, pushing- its way into the vesicular fluid, carries 

 the archosome at its apex, 'l'he vesicular "double jacket" thus formed 

 seems to persist, with its contained fluid, even up to maturation (Fig. 29). 

 In dogs and cats, the archoplasmic vesicle seems also to exist as an 

 exterior cephalic jacket, in relation to the neai'ly mature spermatozoon, 

 the archosome projecting from the exti-emity of the nucleus into the 

 vesicular fluid. A closely similar archoplasmic metamorphosis during 

 the development of the spermatid occurs in all mammals which I have 

 examined; indeed, it forms one of the most constant featui-es troughout 

 the whole change. The rudiments of the process were figured by 

 Brown, and it is more fully dealt with in the all too short contribution 

 to the subject by Benda, already cited. Ih actual effect ò-eems to he 

 the :^eparation of a portion of the solid frameworh of the archoplasm 

 from the ßuid irhich interpenetrateti it (and which appears after the 

 completion of the process as the vesicular fluid). 



It is worth noting how close a parallel exists, on one hand, bet- 

 Aveen the archoplasmic metamorphosis and the formation of the chi'o- 

 mosomes from the resting nuclear reticulum, and. on another, between 

 cytoplasmic phenomena to which 1 have already alluded, most notably 

 that of the origin of dictyosomes in the arthropod Branchipus. 



We must moreover regard this archoplasmic metamorphosis as 

 distinctly purposive with respect to fertilization, since in every such 

 metamorphosis which I have studied; the archosome in retained as a 

 cephalic knob or cap to that part of the nucleus which becomes the 

 extreme anterior extremity of the spermatozoan head, while the resi- 

 dual archoplasm is cast off as a constituent of the residual corpuscle. 

 It would seem therefore essential that this condensed speck of cyto- 

 plasmic origin should be carried, into the ovum during the process of 

 fertilization; and comparison will show that it occupies the same final 

 position as the " sperm ocentre" of Julin, and the spermatic centrosome 

 described by Fick ^) in the Axolotl. 



The residual archoplasm during these changes is, as we have seen, 

 pushed away from the nucleus; it wanders into the remoter cyto- 



') Anat. Anz. Bd. VII. p. 818. 



