DENDEOCOMETES PARADOXUS. 



35^ 



the conjugate contains food vacuoles, and the letter S that its 

 cytoplasm is clear or moderately clear.) 



Number of 

 Slide. 



146 



83, 84 



10 

 129 

 127 

 126 

 122 

 121 



25 

 127 

 120 

 119 



The General Morphology of the Heterokaryote 

 Body.— The investigations of Maupas (20), Biitschli (2) 

 and Keppen (15), notwithstanding the writings of Plate 

 (21), and more recently of Sand (23), have placed beyond 

 all reasonable doubt the zoological affinity of the classes 

 Acinetaria and Ciliata. In these two classes alone there are 

 two kinds of nuclei in each independent organism. In all 

 other Protozoa, with the exception perhaps of a few forms 

 like Pelomyxa, in which there ai-e only scattered granules 

 of chromatin, there is only one kind of nucleus.^ This 

 fundamental distinction of tlie Ciliata and Acinetaria justifies 

 us in placing them together in a subdivision of the Proto- 

 zoa, which ma}'' be called the Heterokaryota (Hickson, 11). 



There may be some difficulty in giving an absolute defini- 

 tion of what is a nucleus. It will be agreed, however, that 

 every structui-e in a protoplasmic mass that contains 



' Cuenot (3) has recently discovered that in a Gregarine belonging to the 

 genus Diplocjstis, which is parasitic in the common cricket, the two forms of 

 nuclei occur. The micronuoleus, however, does not become visible until the 

 onset of sporulation, but it tlien divides by a mitotic process to give rise to 

 the nuclei of the spores, while the meganucleus disappears. 



