CHONDRIOSOMES IN CELLS OF FISH-EMBRYOS 481 



are equallj^ and those in which the chondriosomes are unequally 

 divided between the daughter-cells. To the first category be- 

 long apparently some somat'c cells and obviously the male 

 germ-cells. The equal repartition of the chondriosomes is ob- 

 tained in one of three ways: first, by the formation of rods, or 

 rings, and their bipartition (a most interesting case has been 

 recently described by Wilson — 1916 — in the Arizona-scorpion); 

 secondly, by the scattering of the chondriosomes through the 

 body of the dividing cell, and, finally, by the attribution of an 

 equal number of bodies of the same shape and size to each daugh- 

 ter-cell (Sokolov, '13). In the male germ-cell, any one of these 

 processes may lead, as I pointed out in 1907, to a reduction of the 

 quantity of chondriosomal substance in the spermatids, an opinion 

 which the observations of Sokolov and- of Wilson — on the Ari- 

 zona-scorpion — clearly corroborate. 



A constantly unequal repartition of chondriosomes during 

 mitosis is especially obvious in the ascidian-embryo. Such a 

 behavior is, in my opinion, just as interesting as the phenome- 

 non of the equal repartititon : it illustrates beautifully the im- 

 portance of the division of the protoplasm. There is a sug- 

 gestion that an analogous process takes place in certain male 

 germ-cells, as, for example, in Myxinoids (A. and K. E. Schreiner, 

 '08: see how^ever, the reservations I made, '12, p. 683), or per- 

 haps in the California-scorpion (Wilson, '16). If this were 

 confirmed, I could only recall that I have already propounded the 

 question ('12, p. 683) as to whether such a constantly unequal 

 repartition of chondriosomes between the spermatids may not 

 lead to the formation of two kinds of spermatozoa of different 

 physiological value. 



I will conclude this paper with a few considerations on the 

 structure of the protoplasm. 



From his observations on the centrifuged eggs of Crepidula, 

 Conklin ('17), comes to the interesting conclusion that the 

 ground-substance of the protoplasm, i.e., the protoplasm minus 

 "microsomes, mitochondria, as well as yolk, oil and other inclu- 

 sions," is formed of two parts, one more fluid part (enchylemma, 

 alveolar substance, paramitome, hyaloplasm, trophoplasm) and 



