SPERMATOGENESIS OF PASSALUS CORNUTUS. 421 



the centrosome. The conditions here are very much like those 

 in Passalus (Figs. 19, 38), but in the latter case the deeply stain- 

 ing body is certainly not a centrosome. The sphere (?) of the 

 spermatid of Passalus has no connection with the centrosome. 

 This is in agreement with Montgomery's conclusions in Euschis- 

 tus. According to Munson, the centrosome gives rise to the 

 acrosome of the spermatozoon. 



Payne (1917) has approached the subject of spermatid trans- 

 formation with more or less scepticism as to the generally ac- 

 cepted origins of the structures present here. I am in hearty 

 accord with this point of view, but it seems that Payne has 

 carried matters too far. I agree that to call the structure from 

 which the axial filament grows a centrosome without tracing its 

 history from the second spermatocyte, is highly speculative. 

 But to say, as Payne does, that at a certain stage of the sperm- 

 atid "there is nothing in the cytoplasm but mitochondria" 

 (p. 309) is equally as dogmatic and unwarranted in light of the 

 observations of many other workers. In Passalus there can be 

 no doubt that the centrosome of the spermatic! has actually been 

 carried over from the preceding cell-division. Furthermore, 

 in the youngest spermatid there can always be found the re- 

 ffingent cytoplasmic body which is undoubtedly a spindle 

 derivative. In Gryllotalpa, Payne finds in the stages succeeding 

 the young spermatids which contain no other cytoplasmic struc- 

 tures but mitochondria, the sudden appearance of two deeply 

 staining bodies, one of which later forms the acrosome, while 

 the other is pushed off into the tail. Since these were not 

 present in the earlier stages, they have apparently arisen "de 

 novo," that is, they are newly differentiated parts of the cyto- 

 plasm. One might then expect to find developmental stages of 

 such structures, but Payne does not indicate such. However, 

 it seems to me that the building-up of the spermatozoon from 

 the spermatid is a process involving no differentiation, but a 

 transformation of differentiations already present. All the struc- 

 tures needed in the building up of the spermatozoon are at hand, 

 and there is no further elaboration of new ones. Munson (1906, 

 page 96) has clearly expressed a similar view : 



"The comparative inertness of the nucleus at the close of the 



