412 EDWIN G. CONKLIN. 



Again the way in which the chromatic connection between 

 nuclei unites with the chromosome plate (Figs. 53, 54) shows that 

 this connection is actually composed of chromosomal substance 

 though it has been so modified that it does not give rise to 

 separate chromosomes nor does it show any tendency to divide 

 or split, as normal chromosomes do, into daughter chromosomes. 

 Although it is not possible to count the number of chromosomes 

 in these plates it is evident that it varies in different cases and 

 that in general it is less than normal, which is what would be 

 expected if the chromatic connections represent a number of 

 spun-out chromosomes. Furthermore the fact that these con- 

 nections do not swell up to form vesicles as normal chromosomes 

 do, indicates that the chromosomal substance of which it is 

 composed has undergone some significant change. 



Still later divisions of the cells connected by these chromatic 

 strands are generally abnormal, as is shown in Figs. 55-60. 

 The eggs shown in these figures were subjected to diluted sea- 

 water during the third cleavage and were then returned to normal 

 sea-water where some of the cells have undergone the fourth, 

 fifth and sixth cleavages. In many cases the chromosomes at 

 each of these cleavages have been stretched out into chromatic 

 connections between daughter nuclei and since all of these 

 persist a complicated network of such connections is present 

 between nuclei of successive generations (Figs. 55, 56, 58, 60); 

 at the same time the number of chromosomes in a plate is in 

 many instances greatly reduced (Fig. 55). 



The same types of modifications produced by diluted sea- 

 water persist after the eggs have been returned to normal sea- 

 water and in all of these cleavages, if one saw only the end result, 

 the chromatic connections would seem to indicate that the nuclei 

 had divided by amitosis. However a study of various stages in 

 this process shows conclusively that this is not the case but that 

 all of these divisions are modified forms of mitosis. 



V. CONCLUSIONS. 



i. The modern revival of interest in amitosis is due to a reac- 

 tion against the chromosome theory. If nuclear and cell divi- 

 sions ever take place by amitosis in normally developing sex 



