316 PROCEEDINGS OF THE ACADEMY OF [April, 



acrosome from the cytoplasm. The acrosome in Lepidoptera is 

 formed from two parts — a clearer vesicle and a dark granule, but the 

 idiozome which migrates from the acrosomal region in early develop- 

 ment has not been seen to return, nor has it been possible to trace 

 the sphere material to this region ; it therefore seems most probable 

 that the acrosome in Lepidoptera has been formed from modified cyto- 

 plasm. The chromatin granule noted throughout preceding pages and 

 described as a small granule staining in iron hematoxylin and sur- 

 rounded by a clear zone, is seen in very young spermatids to lie quite 

 near the nucleus and in a position corresponding to the idiozome; in 

 Acronycta this granule moves nearer the head of the nucleus, and a 

 similar granulejs later found within the head piece; the same relation 

 is suggested in the Saturnids. The presence of this body recalls the 

 "chromatin body" described by Lenhossek (1898) as an extruded 

 nucleus of unknown origin which degenerates without taking any part 

 in the formation of the spermatozoon, as well as a similar body shown 

 by the Schreiners (1908) to be present in Myxine. King (1907) finds 

 such a body in Amphibia, traces it from the primary spermatogonia to 

 the acrosome of the spermatozoon, and because of its function names 

 it "acroblast." The extrusion of the chromatin granules from the 

 nucleus during the growth stage like that described for Myxine has 

 here been observed, but although it persists and is traceable through 

 the spermatid, yet further research is required to determine whether 

 this chromatin granule of Lepidoptera is really functional or whether 

 like similar granules described by other workers it plays no part in 

 the development of the sperm. 



The origin of the axial filament from one of the centrosomes of the 

 middle piece was first demonstrated by Moore (1895) for Elasmo- 

 branchs. Paulmier described a similar origin for Anasa and gave 

 proof for this by the discovery of the occurrence in giant spermatids 

 of two and four axial filaments. That the axial filament actually 

 arises from the centrosomal substance, or is formed like astral rays 

 and spindle fibres by a differentiation of the cytoplasm, are the two 

 views most widely held. Meves (1897) in his work on Pygcera accepts 

 the latter view, believing that "die Faden der Schmetterlingsper- 

 matocyten extracellular gewordene Mitomfaden darstellen." The 

 same writer concludes for Lithobius "dass die bei Lithobius beobach- 

 teten Faden sind aus dem einen der beiden Centralkorper durch 

 Langenwachstum desselben, hervorgegangen," and Korff (1899) on 

 Helix and Suzuki (1898) on Elasmobranchs show that the inner 

 centrosome elongates and so support the first view of Meves that this 



