322 C. ISHIKAWA. 



Noctiluca spindle. In the cytoplasm of the spermatocyte ut some 

 distance from the nucleus, there is formed a small spindle, from the 

 poles of which, when it has attained a certnin size, a number of fil)res 

 is seen passing to tlie chromosomes. By growth and change of 

 position, it gradually attains the ordinary form of the spindle with 

 equatorial chromosomes. In this full grown spindle there are thus 

 two sets of fibres : the one continuous iDctween the two centrosomes 

 and lying axially ; and the other passing from the centrosoines to 

 the chromosomes. The latter set of fibres therefore lies more or 

 less like a mantle above the other set, which he calls the central 

 spindle (20, p. 580). When division of the cell is completed the 

 fibres of the central spindle return to the protoplasm (?), while the 

 other fibres collect together to form the archoplasms of the daugh- 

 ter cells. This description of h[eriii(tnn\s stands thus in beautiful 

 correspondence with that of the formation of the spindle in Xocti- 

 luca, given above; but with the difference that in Noctiluca, from 

 the persistence of the nuclear wall, the centnil spindle does not 

 lie, strictly speaking, in the axis of the whole system, but in tlie 

 groove formed on one side of the nucleus by the depression of its wall, 

 and therefore the mantle-like fibres as well as the chromosomes do not 

 lie quite around the axial spindle. Tl\is otherwise exact correspon- 

 dence of the spindle fibres in these two widely different animals is, 

 beyond all doubt, a very interesting phenomenon, and renders desi- 

 rable, in my opinion, further investigations into the structure and 

 formation of different kinds of cells in other animals and perhaps also 

 in plants. 



In this connection I nuist not leave unnoticed the question of the 

 V('rhindi(N(j!>fa(lfn, of whose origin there are also as many interpretations 

 as there are questions on other matters. Many investigators, such as 

 0. Hertiri,! [2\, 22\ Boven {3\ Ed. ran Jkneden and Nejit (\\ and 



