148 J. J. LISTER. 



January 12, 1894), including a large number in some stage of 

 the reproductive phase, not one has presented itself which 

 showed an intermediate condition between that with seven 

 comparatively large nuclei and those with multitudes of minute 

 nuclei of minimal size. 



Although the conclusion is founded on negative evidence, it 

 seems clear that the view that the small nuclei of the later 

 stage are derived from the large nucleus by binary fission is 

 untenable. 



It seems not imjDOSsible that the presence of more than one 

 large nucleus in the megalospheric form may be due to an 

 accidental division having occuiTed in the process of passing 

 from one chamber to another. The nucleus, which is a very 

 plastic body, is often found with two or more processes extend- 

 ing into the chamber adjoining that in which the body of it lies, 

 through the connecting canals. In the ordinary course, the 

 nucleus must eventually take to one canal, any processes which 

 may have extended into other canals being withdrawn, but it 

 might occur if the forces propelling it onward were evenly 

 balanced that a separation into two halves should take place. 

 However this may be, I am inclined to think that the condition 

 with multiple nuclei is not a necessary stage in the life-history, 

 and may therefore to that extent be regai-ded as abnormal. 



It appears probable that an indication of the fate of the 

 large nucleus as an entity is given by those cases in which the 

 nucleoli have decreased in number, its shape has become 

 ii-regular, and its staining properties diminished (fig. 26). In 

 such cases a large part of the substance of the nucleus appears 

 to have passed into the protoplasm, while the remainder is in 

 process of dissolution. 



In what manner the nuclear material dispersed in the 

 protoplasm becomes fashioned into the small nuclei of the later 

 stage I have no evidence to show. 



[Rhumbler has recently published an account (28, b) of his 

 investigation of Saccammina sphcerica (M. Sars), in which he 

 has obtained a much more complete history of some of the 

 nuclear changes than I have succeeded in doing. 



