100 THE MICROSCOPE. July, 



presents some teeth imbricated with geometric regular- 

 ity. The toothed wheel of the Trichodines surpasses ia 

 regularity and fineness the most precise work of watch- 

 making. It acts as an organ of support, and possesses, 

 with the striated cup, the property of giving to the body 

 of this being the rigidity of which it has need. The 

 Trichodine, like all ciliated infusoria, multiplies itself by 

 direct division. Its entire body separates itself in two 

 equal parts, which form two new individuals similarly 

 constituted. In this process, the ciliated membrane, 

 the striated cup and the toothed wheel undergo a com- 

 mon destiny; they separate themselves and divide 

 themselves, showing by this that, in spite of their ap- 

 parent rigidity, they are formed of a still living jDroto- 

 plasm and not of a substance secreted by the hydra. 



Such, in a few words, are the characteristics of the 

 parasite of the fresh water hydra. The Trichodines, 

 discovered and described by Trembly as the louse of the 

 hydra in 1744, can be taken as a type of a numerous 

 family of ciliated infusoria, the Urecolaires (fig. 3), whose 

 common characteristic is an adhesive organ, more or 

 less complicated and analagous to the one we have been 

 studying. 



In some of these species (figs. 3-5) the toothed wheel 

 is replaced by a simj^le ring of support; in others a 

 membrane complementary to the collar takes the place 

 of the long, stiff hairs which stand up around the body, 

 but all live as parasites upon the surface or on the inter- 

 nal organs of aquatic animals of either fresh or salt 

 water. Fig. 4 shows Liemofjhora, a parasite of Ophiura 

 squammata. Fig. 5 represents the interior of its adhes- 

 ive disc. 



The meeting of the American Microscopical Society at 

 Ithaca August 21, 22, 23 will exceed all others in interest. 

 Be sure to go. 



