168 CYTOPLASMIC INCLUSIONS 



that none of them has been traced to Golgi bodies, mitochondria, or 

 segregation bodies — i.e., they do not react with osmic acid, Janus green 

 B, nor neutral red. It is evident that not all important segregation nor 

 synthesis is revealed by these stains. 



The mucus granules of Euglena (Dangeard, 1928) and the pellicular 

 secretions of Vortkella (Finley, 1934) stain with neutral red and thus 

 might be classed the segregation granules of Opalina and others, the 

 only difference being that in the former is segregated mucus, which is 

 not used within the cell but is extruded in the normal functioning of 

 the protozoon, while in the latter are segregated proteins, which are 

 normally used within the cell. It is interesting, however, that Kedrowsky 

 found that when the segregation granules were filled with foreign ma- 

 terials, such as the organic silver compounds, the granules are extruded. 

 The expulsion of droplets containing neutral red may be induced in 

 Paratnecium (Frisch, 1938) and other ciliates. These examples indicate 

 that the formation of the segregation granules and the secretion granules 

 is comparable, the only difference being that in one the material is used 

 internally and in the other externally. 



The Granular Complex 



The detailed consideration of each of the types of cytoplasmic gran- 

 ules has resulted in the conclusion that there are no universal cyto- 

 plasmic components and that each of the terms mitochondria, Golgi 

 bodies, neutral red granules, and so forth has been applied to a hetero- 

 geneous assortment of granules of widely different functions. This con- 

 clusion, derived from a consideration of the types of granules separately, 

 becomes inescapable if we consider the whole granular complex. The 

 problem is on the surface one of classification, but fundam.entally it is 

 one of function — what functions are performed by cytoplasmic gran- 

 ules, and is the same function always performed by the same type of 

 granule in different Protozoa.'' Since these granules are not independent 

 units but are part of a granular complex which in turn is a part of 

 the whole cell, this whole complex must be considered in seeking an 

 answer to these problems of function. The investigations which seem to 

 be suitable for this comparison are those of Mast and Doyle (1935a, 

 1935b), Holter and Kopac (1937), Holter and Doyle (1938), all on 

 Amoeba proteus; Hopkins (1938a, 1938b) on Flahellula mira; Ked- 



