714 CALKINS. [Vol. XV. 



detachment from the mother-animal, and a part of it becomes transformed 

 into the flagellum, just as in many vegetable swarm-spores, as Strasburger 

 shows. 



16. In the center of the archoplasm is generally seen a centrosome, 

 which often shows a dumb-bell form. Sometimes, however, two centro- 

 somes are found in the archoplasm of the spore-forming cells. In many 

 cases, again, there is found in the center of the archoplasm a number of 

 small oval rod-shaped or curved bodies staining exactly like centrosomes, 

 instead of one or two centrosomes. These may represent the group of 

 centrosomes of Heidenhain. 



17. The origin and the fate of the centrosome are not known. In a few 

 instances it appears to be formed from the nucleus.' 



Section 5 is rather obscurely worded, but, from the detailed 

 description given elsewhere, it appears that the chromosomes, 

 which are of various lengths, consist of irregular rows of micro- 

 somes lying scattered throughout the nucleus. "The chromo- 

 somes, except a few, do not seem to lie in definite order, but to 

 be scattered more or less irregularly in the nucleus." 



In the descriptive part of Ishikawa's paper section 7 is 

 stated in a more conservative manner : " While the chromo- 

 somes of the nuclei of the dividing individual are represented 

 by a double row of microsomes, those of the nuclei of the 

 spore-forming individuals appear to consist of four rows." He 

 explains this difference as follows : " In division the nucleus 

 has to divide only once, and hence the chromosomes require 

 only once to divide, while in the spore-formation divisions of 

 the nucleus take place rapidly one after the other, and two 

 divisions take place almost simultaneously " (/. c, p. 304). 



It may be pointed out, however, that in spore-forming indi- 

 viduals the nuclei continue to divide rapidly and without inter- 

 vening resting periods, until there are from three to five 

 hundred descendants of the original nucleus. What reason,' 

 therefore, can there be for quadruple division of the original 

 chromosomes .-• 



The details regarding formation of the nuclear plate and the 

 separation of the chromosomes are not given. 



1 The killing agents used by Ishikawa were Flemming's stronger solution, 

 picro-acetic, and acetic acids. The material was stained with Bohmer's haema- 

 toxylin, acid fuchsine, methylin blue, and methylin green. 



