Art. 6.— I. Hveda and Y. Ozaki: 



the first division is invariably amitotic and the second and third 

 mitotic, these latter giving rise to numerous fine chromatin threads, 

 while in ex-conjugants the micronncleus divides always mitotically 

 and gives rise to four distinct chromosomes. The third point 

 seems to be particularly noteworthy, since it involves facts which 

 seem to suggest an explanation as to the mutual relation of mitosis 

 and amitosis both ontogenetically and phylogenetically. It is 

 interesting to note that Lapage and Wadswoeth^^ have recently 

 reported from Dendrocometes paradoxus an interesting case of the 

 heterogeneity of micronuclear division, which is, however, less com- 

 plicated than the present case. According to the authors, distinct 

 chromosomes arise in the divisions during conjugation, while in 

 the divisions during bud-formation there appear simple minute 

 chromatin granules instead of chromosomes. 



To begin with the changes of the micronncleus, loading to 



the formation of the conjugation- 

 spindle, When two conjugants come 

 into mutual attachment, the micro- 

 nucleus (fig. 2, n), which is still in 

 its original position, begins to swell. 

 Then the entire micronncleus gra- 

 dually elongates, first into an ellipti- 

 cal shape and later into that of a 

 bow with swollen ends (fig. 3, n). 

 The micronuclecs thus transformed 

 finds its place always on one side 

 V";v,. ''• of, and closely to, the meganucleus 



(iV), which has up to this moment 



Fiep^res 2 —13 relate to the coujnga- , . 



tion/ iron-hœmatoxylin. remained unchanged m position and 



Fig. 2. 



\ -"; 



.V 





u 



1) Lapage, G., aud Wadswobth J. T.— On Denlrocometes paradoxus ; Part II, Reproduction. 

 <l. J. M. S., Vol. 61, 1916. 



