CYTOPLASMIC INCLUSIONS 179 



are proHucts of the macronucleus, mitochondria, and so forth. This is a 

 difficulty which cannot be overcome until the fundamental processes 

 which are involved have been worked out. 



In addition to these granules are a heterogeneous group of unknoivn 

 granules such as the alpha granules of Amoeba, and the accessory bodies 

 formed by the neuromotor system of Haptophrya (Fig. 70); various 

 pigment granules, which may in some cases be part of the lipoid reserves, 

 or in some cases residues of food, as in Plasmodium and Ichthyophthirius, 

 this latter type of course not being true cytoplasmic granules. Crystals 

 also are often present, the ones in Amoeba being classed as a part of 

 the protein reserves (although here there is a question, since they orig- 



Figure 70. Accessory 

 bodies being formed from 

 the neuromotor ring in 

 Haptophrya m'tchiganens'is, 

 Zenker's haematoxylin. 

 (After Bush, 1934.) 



inate in the food vacuoles) on the evidence of Mast and Doyle. Other 

 crystals, according to Reichenow, may be excretory granules. 



Comparison with Cells of the Metazoa 



Cytological investigations in the Protozoa have always been influ- 

 enced by the transfer of concepts originally developed from a study of 

 the cells of the Metazoa, particularly the vertebrates, with the result that 

 the division of granules into mitochondria, Golgi bodies, vacuome, and 

 passive reserve bodies are as common in the literature of the Protozoa 

 as in that of the Metazoa. In spite of Dobell's denial of the cellular 

 nature of the Protozoa, any consideration of the granules of the Protozoa 

 necessitates a comparison with the cytoplasmic granules in other animal 

 cells. 



The lack of a "typical" reticular net of Golgi in the Protozoa, the 

 infrequency of filamentous mitochondria, and other striking morpho- 

 logical differences between the protozoan and metazoan cells have been 

 stressed so often that it is well to present several cases of equally striking 

 similarities in both structure and function. Volkonsky (1934) found 



