INFLUENCE OF GLANDl LAM I-.XTK.M I ->. 23 



remain constant in form and structure. While the reservoir 

 appears always in the same place, its walls are formed of new 

 substance at each pulsation. There is much controversy as to 

 the exact nature of the enveloping material, Kent (16) ciid 

 Carter, Ehrenberg, Siebold, Claparede and Lachmann as be- 

 lieving in the presence of a morphologically distinct investing 

 membrane, while Maupas (20), Ehrmann (8), Degen (6), and 

 Minchin (21) upheld the conflicting view that the vacuole is 

 simply a drop of watery fluid lodged in, and bounded by a more 

 viscid protoplasm. Maupas found the wall comparable to that 

 of a soap-bubble, since according to him, the viscid proto- 

 plasm is distended by increased pressure until it breaks at the 

 weakest point, the excretory pore. The rhythmic contractions 

 he believed due merely to the innate irritability of the protoplasm 

 in response to a specific stimulation. According to Biitschli's 

 alveolar theory of protoplasm (3) the behavior of the vacuoles is 

 explicable entirely by the physical law r s of fluid masses. An- 

 drews (i) developed the application of this theory, describing 

 the rhythmic variation of viscosity in the pcllicular membrane 

 of the contractile vacuole: 



"At times in the rhythm the vacuole actually disappears, and 

 during collapse the pellicular substance becomes so completely 

 relaxed, so fluid, that it mingles with the interalveolar substance 

 of the surrounding protoplasm. As the membrane reforms after 

 such collapse it thickens and is gradually augmented by interal- 

 veolar stuff. As a contractile pellicle it is subject at all 

 times to the same flow of its substance as is the surrounding net- 

 work, and is at times so modified in structure and reaction as to 

 form an' area of organized physiological reaction." 



Claparede and Lachmann believed that the vacuole has no 

 intercommunication with the surrounding medium, while 

 Carter and Lankester (18) held that the vacuole discharges 

 externally at the time of collapse. Wrzesniowski (30) Maupas 

 (20), Butschli (3) and Hance (11) definitely described the pore- 

 like character of the communication. Jennings (14) proved 

 this inter-communication conclusively by demonstrating the 

 discharge of the vacuole into a surrounding medium of dilute 

 india ink. 



