THE CONTRACTILE VACUOLE 439 



MacLennan (1933) found that the osmiophiHc granules contribute di- 

 rectly to the formation of accessory vacuoles, which in turn form the 

 contractile vacuole. With respect to the possible function of the vacuole, 

 he states (p. 236): 



The vacuolar region found in these ciliates shows definite evidence of the 

 elimination of materials by means of the vacuolar fluid and corresponds to 

 the secretary region or "region of Golgi" in gland cells. The nature of the 

 materials eliminated by the vacuolar region was not determined in this in- 

 vestigation. Since, however, the pellicle in the Ophryoscolecidae has been 

 shown to be relatively impermeable and since the vacuolar region is the 

 only demonstrable path by which materials are constantly being passed to the 

 exterior, it is likely that the katabolic wastes of these ciliates are eliminated 

 by this organelle rather than by direct diffusion through the pellicle. 



Dunihue ( 1931 ) found that the vacuole system in Paramecium cauda- 

 tum is osmicated only after the neutral-red stainable globules. These 

 globules and Janus-green stainable elements, he believes, represent the 

 vacuome and chondriome (mitochondria) respectively. King (1935) 

 noted a "specialized excretory protoplasm" surrounding the feeding 

 canals in P. multimkronucleata, but denied that this material is ho- 

 mologous with the Golgi apparatus of metazoan cells. 



The opinions of von Gelei (1925, 1928) concerning the structure 

 and function of the contractile vacuole in Paramecium are of special 

 interest. He described essentially the same structures in stained Para- 

 mecium as those mentioned by Nassonov. The zone of specialized plasma 

 around the distal portion of the canals, particularly, was described in 

 detail, and an excretory function assigned to it. This specialized plasma 

 von Gelei calls "nephridial plasma," its excretory function being implied 

 by its name. This "excretory" function von Gelei believes is entirely dif- 

 ferent from the "secretory" function assigned by Nassonov, when the 

 latter considers the specialized plasma to be the Golgi apparatus. This 

 disagreement appears to be imaginary rather than real, since an analysis 

 of their respective views indicates that the two authors observed struc- 

 tures which are identical in practically every respect; but to describe the 

 function, they selected different words. Moreover, these different words, 

 when translated into terms of physiological processes, are practically iden- 

 tical. Von Gelei pictures two different arrangements of the deeply stain- 

 ing material in this zone of specialized plasma; in one the stained ele- 



