No. 3.J STUDIES ON CEPHALOPODS. 277 



blastoderm. The descriptions of the different stages, which are 

 but summarily given in connection with the few diagrams, will 

 be suplemented in a future paper on the caryokinesis in Cephal- 

 opods and Echinoderms. 



The preceding descriptions of the phenomena of caryokinesis 

 in Cephalopods refer to four important topics : (i) the origin of 

 the spindle ; (2) its behavior towards the nucleus ; (3) the forma- 

 tion of the equatorial chromatic " plate " ; and (4) the separa- 

 tion of the daughter plates and the formation of the interzonal 

 filaments. 



I have attempted to show that these series of phenomena are 

 the continuation of one and the same process, with no reversal 

 of activity in the middle, nor with the introduction of several 

 hypothetical factors. 



The spindle, however, plays only a part in the production of 

 the caryokinetic phenomena. The whole behavior of the chro- 

 mosomes preparatory to division, such as the transformation 

 from a resting condition to a coil stage, followed by the longi- 

 tudinal splitting of each filament, — phenomena which take 

 place independently of the influence of the spindle, — has 

 received no consideration, and, so far as I can see, has no 

 causal connection with the behavior of the archoplasm, although 

 both tend to accomplish the same end, viz. the formation of two 

 nuclei out of one. It is conceivable that one mother coil may 

 sometimes split into two different kinds of substances, and the 

 archoplasmic filaments play simply the part of a distributing 

 agent in carrying these into opposite halves of the dividing cell. 

 In view of the general theoretical conclusion regarding the inti- 

 mate correlation between form and matter, and mechanism and 

 function, such a view does not appear improbable ; for, as has 

 already been stated, the differences of two cells lie in their 

 structure, and the structure being the expression of the chemi- 

 cal substance of the protoplasm which composes them, wher- 

 ever we find the difference of structure we find difference of 

 substance or substances, and wherever we find difference in the 

 substance we find difference in property or function. It is 

 probable, as has been mentioned already, that the nuclear sub- 

 stance, by its constant metamorphoses, gives rise to a series of 

 substances, to isolate and distribute which is the function of the 

 spindle, a number of differently constituted cells being thus 

 produced. 



