XV, 4 



De Leon: Balantidium Haughwouti 



401 



or areas of achromatinic substance. The whole is inclosed in 

 a delicate nuclear membrane. 



Fig. 3. a, b, and e, Meganuclei of the reticulate type (a, superficial; b, middle; and c. deep 

 focus) ; d, e, and /, optical sections of a reticulate meganueleus ; g, meganueleus viewed 

 from its convexity ; note the extreme thinness of the "crown" of the nucleus under which 

 lies the micronucleous ; h, bipartite meganueleus ; micronucleus partly shown ; t and j, 

 meganuclei of granular type ; k, meganueleus of aiveolar type. 



The finer structure of the meganueleus, as seen in the normal 

 vigorous infusorian, is that of an evenly distributed network of 

 chromatin granules compactly arranged. This structure is, of 

 course, only demonstrable in well-stained and properly extracted 

 preparations. Irregular clumping of the chromatin into a series 

 of groups which gives the appearance of a vacuolated nucleus 

 has been interpreted by various investigators as supervening on 

 unfavorable conditions and as presaging disaster to the organism. 

 I see no support for such a supposition in this instance. All 

 the individuals showing a nucleus of this type were vigorous- 

 appearing cells, exhibiting no signs of the vacuolation and dis- 

 tortion so characteristic of the infusorian cell in distress. 



In addition to the regular series of incurving forms, other 

 striking and interesting changes are seen in the structure of 

 the meganueleus. Individuals have been seen in which there 

 were two well-formed meganuclei in the cell. I am inclined to 

 interpret this as, possibly, a result of abnormal distribution of 

 the meganuclear anlagen in the ex-conjugant stage following 

 syngamy, which process, however, I have not observed. 



