CYTOPLASMIC INCLUSIONS 175 



Golgi bodies, and the vacuome. The rejection of the universahty of any 

 one of these components still leaves the possibility that in each cell there 

 are two sets of granules — the group which is permanent in organization, 

 and a group of temporary granules, usually "passive" reserve bodies, 

 which may be derived from the activities of the first. This is not a 

 restatement of Altmann's theory, in the sense that it implies that the 

 first group are living units as such, nor even that these granules are 

 regarded in any strict sense as independent, since their maintenance 

 obviously depends upon their interaction with the other parts of the 

 cell. The question is whether any set of granules are present during the 

 whole life cycle, and further whether new granules of the same group 

 arise directly from the old granules and never arise de novo. 



The morphological studies of Faure-Fremiet (1910), Joyet-Lavergne 

 (1926a), MacLennan (1934), Subramaniam and Ganapati (1938), and 

 others have shown that mitochondria, Golgi bodies, glycogen granules, 

 and so forth, in various Protozoa, undergo division in such a manner as 

 to retain the original organization of the granules, and that these bodies 

 are found in all stages of the life cycle. On the other hand. Horning 

 (1929), Volkonsky (1929 on), MacLennan (1936), and Kedrowsky 

 (1931 on) find that one or more of the supposedly fundamental com- 

 ponents arise de novo either continuously or at some stage of the life 

 cycle. A de novo origin has been proved by Mast and Doyle ( 1935b) not 

 only for granules which are simple morphologically, but even for the 

 complex tripartite refractive granules of A. proteus. In Ichthyophthirius 

 apparently none of the granules are retained through the life cycle, thus 

 clearly eliminating in this protozoan any distinction based on continuity. 

 These morphological studies show that there may be a genetic continuity 

 with respect to some granules in some of the Protozoa, but that it is not 

 a general thing. 



The observation that in some Protozoa all of the granules arise de 

 novo at some time or other, raises the question whether the observed divi- 

 sions are significant or are merely incidental. Kedrowsky was able to in- 

 duce typical division figures in the endosomes of Opalina by altering the 

 culture medium. Horning (1929) showed that dividing mitochondria 

 are found m the trophozoite of Monocystis but that these granules dis- 

 appear completely during the spore stages and form de novo in the 

 newly liberated sporozoite. The digestive granules of Ichthyophthirius 



