MUSEUM OF COMPARATIVE ZOÖLOGY. 157 
Zellenvermehrung führen kann.” When, however, both mitosis and 
amitosis occur in the same tissue, he considers it probable that only the 
former is the normal method of regeneration and of growth. 
The brief papers by Löwit, Verson, and Frenzel are replies to Ziegler’s 
C91) recent article on amitosis, and contain little that is new. Verson 
describes briefly the early stages in the spermatogenesis of the silkworm 
(Bombyx mori). He states that the spermatocytes originate from a 
single large nucleus (“ Riesenkern”), which divides repeatedly and 
unequally by amitosis. The small daughter nuclei thus produced divide 
by mitosis, and at length form the spermatocytes. Frenzel adduces 
instances of amitosis in the intestinal epithelium of Crustacea and 
Insects which do not fall within Ziegler’s generalizations. 
Vom Rath’s paper is a valuable contribution to our scanty knowledge 
of the occurrence of amitosis in spermatogenesis. He shows very con- 
clusively that, in the testis of the crayfish, amitosis does not oceur in 
the generations of sperm-forming cells, but only in abortive nuclei 
(“ Randkerne ”), which soon degenerate into an amorphous mass. If 
such a fate could be established for all amitotically dividing nuclei in 
the testes of animals, it would be much easier to form a logical estimate 
of amitosis. 
