440 THE CONTRACTILE VACUOLE 



ments are in the form of short rods, which lie with their long axes at 

 right-angles to the long axis of the filling canal, in much the same manner 

 as the bristles of a test-tube brush are arranged with respect to the wire 

 handle to which they are attached; and in the other, these elements are in 

 the form of a net surrounding the filling canal. It is interesting to note 

 that this net-like arrangement is commonly seen in the Golgi apparatus 

 of many metazoan cells, as well as in Dogielella. Von Gelei (1933) ob- 

 served in Spath'idiiim giganteum that not only the contractile vacuole and 

 the smaller vacuoles in its immediate vicinity possess osmiophilic walls, 

 but also others further removed. One can but wonder if this represents the 

 origin of contractile vacuoles by the coalescence of secondary vacuoles, 

 which have arisen in more or less remote parts of the organism. 



In Monocystis ag'dis and M. ascidiae, Hirschler (1924) identified two 

 kinds of lipoid bodies. The smaller of these he considers mitochondria, 

 the larger the Golgi apparatus. In Gregarina polymorpha, G. blattarum, 

 and Spirostomum amhiguum only one kind of lipoid body was ob- 

 served. From this Hirschler concludes that the latter are representatives 

 of a more primative state, in which lipoid bodies are not yet differenti- 

 ated into mitochondria and Golgi apparatus. 



In most instances in which description of structures are given in suffi- 

 cient detail, and in which organisms have been subjected to a variety 

 of stains as well as osmium and silver impregnation, very strong evi- 

 dence has been presented to indicate that contractile vacuoles derive the 

 fluid which they expel to the exterior from granules which are osmio- 

 philic, argentophilic, and sometimes neutral-red stainable. In some cells 

 the osmiophilic granules are aggregated around the vacuole or in that 

 part of the cell in which the vacuole ordinarily arises; this is usually 

 associated with the origin of the vacuole in a restricted portion of the 

 cell. In other cells the osmiophilic granules are dispersed to a greater 

 or less extent, sometimes apparently uniformly throughout the cytoplasm; 

 this is usually associated with at least the potential origin of vacuoles in 

 almost any part of the cytoplasm. Evidence bearing on the subject indi- 

 cates that these osmiophilic granules may represent at least one type of the 

 "excretory granule" so frequently mentioned in the literature. 



Several authors have reported osmiophilic substances in the form of 

 relatively broad bands, or rings, which may or may not be in direct 

 contact with the vacuole wall. Most authors seem to agree that the usual 



