20 



Art. 6.— I. Ikeda and Y. Ozaki : 



Fig. 19. 





It is interesting tliat we have frequently met with individuals 

 with supernumerary moganuclei, in which the micronucleus (fi^.'^ 

 19, ?z) was found to contain four distinct chrotnosomes, though- 

 showing no distinct karyokihetic figure. 

 In the individual shown in fig. 19, of 

 the three meganuclei (iV) present, two 

 have their contents remarkably less strong- 

 ly stained than the third ; this probably 

 indicates that the two are in the process 

 of degeneration. We have also met with 

 individuals in which the supernumerary 

 meganuclei are degenerating still further, 

 while the microriuclear contents are found 

 in the normal state, i.e., forming a com- 

 pact mass. Now, judging from the fact 

 that in the ordinary fission the micro- 

 nucleus divides first and then the mega- 

 nucleus in its turn, the above case may 

 be interpreted in this way, that in those 

 individuals the micronuclear division and 

 consequently the fission of the body have been suppressed probably 

 owing to a certain abnormality in the physiological condition of 

 the organism, and this has caused the fragmentation of the over- 

 grown meganucleus. ' - 



Not infrequently the meganucleus of the present species -l^ 

 seen to perform chromidia formation. In this case the mega- 

 nucleus contains an unusually small number of chromatin granules' 

 in the periphery, and in the central parts very large compact 

 chromatic masses numbering more than two. These central chro- 

 matic masses later leave the meganucleus and come into the^ 

 cytoplasm in which they are probably absorbed in the end. ikî 



In this individual, the micro- 

 nucleiis (n) is forming 4 chromo- 

 somes, but shows no other signs 

 of division ; I faintly stained 

 liiegannclei are in the process of 

 <legeneration 



