CYTOPLASMIC INCLUSIONS 



167 



cytoplasm. It was demonstrated that the reserve plates have no connection 

 with either the mitochondria or the neutral red globules. 



The cyst of Ichthyophthirius is secreted in two parts: first a homo- 

 geneous clear membrane is formed (Fig. 68) and then individual 

 fibrils are extruded, apparently between the bases of the cilia (Mac- 

 Lennan, 1937). These sticky fibrils are stroked into rope-like fibers, 

 which adhere to the under side of the outer membrane (Fig. 69) by 

 the activities of the cilia. Although seven types of granules were demon- 



O © «) (») ill 



67 



wmrmmm 



66 



69 



Figures 67-69. External secretion. Figure 67, inclusions in Euglypha alveolata, prob- 

 ably representing the formation of reserve shell plates (after Hall and Loefer, 1930) ; 

 Figures 68-69, secretion of the cyst wall in Ichthyophthirius multifiliis ; Figure 68, 

 section of early stage showing only the homogeneous layer; Figure 69, section of 

 later stage showing the addition of the fibrillar layer (from MacLennan, 1936). 



strated, no granules could be associated with the secretion of this cyst. 

 In Nyctotherus, variations in the thickness of the secreted cyst may be 

 correlated with the distribution of ectoplasmic structures (Rosenberg, 

 1937), but no granules responsible for the secretion were noted in this 

 form either. The lorica of Folliculiria ampulla is likewise secreted in the 

 form of a clear fluid, which hardens to form a membrane just beyond 

 the tips of the somatic cilia ( Faure-Fremiet, 1932). 



The secretion of vacuoles of oxygen in Arcella is not associated with 

 granules, but with nongranular regions of hyaloplasm, and is probably 

 a result of oxidative and reductive processes of the cell (Bles, 1929). 



The most striking aspect of these examples of protozoan secretion is 



