MUNSON: SPERMATOGENESIS OF PAPILIO. 
Ill 
The principal question concerns its nature and origin, and the part 
it plays in the formation of the sperm. Says Wilson (’02): “The 
confusion that has arisen in this difficult subject is owing to the fact 
that the spermatid may contain, besides the nucleus and centro- 
somes, no less than three additional bodies, which were endlessly 
confused in the earlier studies on the subject. These are the Neben¬ 
kern, the attraction-sphere idiozome (Meves) and the chromatoid 
nebenkorper (Benda);” 
La Yalette first came to the conclusion that the nebenkern originates 
in the Cytoplasm, a view which was later accepted by Nussbaum (’84) 
in the crayfish, by Keferstein (’66) in pulmonates, by Lenhossek (’98) 
in the rat, — by Biitschli (’71), Balbiani (’69), and Metschnikoff 
(’68) in arthropods, and by Auerbach (’96) in Paludina. 
On the other hand it has been held by many that the nebenkern 
has a nuclear origin. Van Beneden and Julin (’84) attributed such 
an origin to it in Ascaris, Grobben (’78) in decapods, and Lee (’88) 
in Sagitta. Attempts have been made to homologize the nebenkern 
with the yolk nucleus of eggs, and consequently it has been thought 
to have a similar origin. So far as I have been able to ascertain there 
is no similarity between the two as regards origin, but the history of 
the two is precisely the same, namely, absorption as food. 
It appears that the majority of writers now take the view that the 
nebenkern is a-remnant of the achromatic spindle after the last division 
of spermatocytes to form spermatids. This is the conclusion which 
my preparations have led me to adopt. The evidence is so strong 
that there is scarcely any room for doubt. 
Plainer (’86) has shown that the nebenkern of authors has meant 
different things; that it consists of two parts, the centrosome at the 
pole of the spindle, and the remnant of the achromatic spindle 
which he names, very appropriately it seems to me, the mitosome. 
Prenant (’87) in a series of studies on pulmonates and reptiles has 
arrived at the same conclusion; also Meves (’97a) in Salamandra. 
Henking (’91) attempts to show that in Pvrrhoeoris, the nebenkern 
is derived from a yolk-like substance existing in the cytoplasm and 
especially surrounding the nucleus, which gradually aggregates into a 
sphere after karvokinesis. I have seen no evidence of yolk bodies such 
as these in Papilio rutulus. Wilcox (’96) professes to have seen, in 
Caloptenus, evidence of the yolk-like substance forming at least part 
of the nebenkern, and the same seems to be inferred in Paulmier’s 
(’99) work on Anasa. 
