268 CHAS. W. HARGITT, 



While the mere absence of mitotic figures at a certain stage in 

 the development of the egg embryo may not warrant a dogmatic 

 assertion as to amitosis, it would seem that the several series of 

 evidences above cited and the easy demonstration of mitosis at a 

 preceding stage strongly suggest its probability. 



But other cases are not wanting which more or less warrant the 

 conclusion that amitosis as a cytologic phenomenon is not restiicted 

 to degenerating tissues or cells, tho perhaps better known in such 

 connection, nor yet to the fairly well established facts of spermato- 

 genesis. There seems no longer reason to doubt its occurrence at 

 least in certain phases, in early embryonic development. 



The convincing researches of Meves (1898) and others in sper- 

 matogenesis would seem to leave little doubt that the amitosis ad- 

 mittedly occurring here involve the spermatogonia no less than the 

 nutritive, or supporting cells (Sertoli cells). 



Similar observations are not lacking concerning amitosis in oogenesis 

 and in the early history of the embryo. Eisig's (1899) recent paper 

 on the development of the "Capitelliden" affords substantial evidences 

 of amitosis in several stages of early development in these annelids, 

 as did the earlier paper of Wistinghausen (1891), on the development 

 of Nereis. 



Meisenheimer's recent paper 1902, on the development of the 

 "Pantopoden" shows a condition following the cleavage similar in 

 many respects to that found in Eudendrium, in which following a 

 partial invagination resembling gastrulation there is formed apparently 

 by amitotic cell division an "inner cell-mass" from which there are 

 later differentiated the entodermal and mesodermal tissues and organs. 



Heatiicote (1886) in describing the development of Juhis gives 

 phases of nuclear origin and migration which likewise seem to have 

 points in common with Eudendriiim, the nucleus becoming indistinct 

 and apparently dividing amitotically. 



Herrick (1892, development of the Macroura, p. 397) has described 

 a condition in the development of Alpheus minus, which likewise has 

 features comparable with those in Eudendrium. To quote briefly in 

 his own words. "Division appears to be direct and irregular. At a 

 somewhat later stage the phenomena of the most interest occur. Each 

 product of the first nucleus has developed a swarm of nuclear bodies 

 which seem to arise by fragmentation. These bodies take the form 

 of spherical nuclei in clear masses of protoplasm", and later constitute 

 a considerable portion of the entire egg. 



