166 CYTOPLASMIC INCLUSIONS 



be called simply protein reserve bodies, a usage found convenient by 

 Joyet-Lavergne (1926a). At the same time, it should be recognized that 

 a reserve function is the one most easily identified by morphological 

 methods, and that other functions must be investigated. The presence 

 of dehydrogenase (Krijgsman, 1936) in protein granules of Trypano- 

 soma evansi is one definite lead. 



The protein reserve bodies are as catholic in origin as in structure and 

 may result from the activities of the segregation granules, macronucleus, 

 mitochondria, or food vacuoles, or may be independent of other formed 

 bodies. The crudity of our knowledge of cytoplasmic granules is illus- 

 trated by the fact that no suggestion of the significance of these differ- 

 ences can be made. 



External Secretion 



This important cytological subject has been greatly neglected in the 

 Protozoa and is generally ignored in a discussion of the protozoan cyto- 

 plasm, except as the vacuolar apparatus is considered to be a secretory or- 

 ganelle. It is an important subject in itself and is most nearly comparable 

 to secretion studied in the Metazoa. 



The attaching organs, or at least the cementing portion, of sessile 

 Protozoa are secreted structures. Just preceding the formation of the 

 peduncle of Campanella, granules are found in the basal region (Faure- 

 Fremiet, 1905 ) . Tintinnopsis nucula is cemented to the lorica by a mucus 

 secretion which is derived from basophilic granules in the stalk (Camp- 

 bell, 1926). 



The lorica of Favella is likewise derived from cytoplasmic granules 

 (Campbell, 1927). Granules which are to form the new lorica accumu- 

 late near the mouth, in dividing animals. After division these are forced 

 out through the cytostome, expand, fuse, and harden. At the same time 

 fecal pellets are molded into this secreted material and the whole lorica 

 is shaped by the activities of the motor organelles. There is in this form 

 a local zone of secretion, as in gland cells, not a general secretion over 

 the whole surface. 



The shell of Eaglypha is formed from separate shell plates, which are 

 secreted within the cytoplasm (Hall and Loefer, 1930). They appear 

 first as small refractive spheres in vacuoles, then enlarge and elongate to 

 become typical shell plates. (Fig. 67). The finished plates lie free in the 



