324 M. N. Lieberkuhn on the Anatomy of the Infusoria. 



perceive near the surface a quantity of light streaks, which 

 run top:cthcr towards the contractile vesicle from the anterior 

 and posterior parts of the body, in more or less considerable 

 curves. In each streak we detect an extremely delicate but 

 perfectly distinct canal, terminating ultimately in the contractile 

 vesicle ; its walls and its contents are readily distinguished by 

 their different refractive power. AVhen one of these canals is 

 traced backwards from its orifice, we may often perceive, after 

 it has run a short distance, a ramification ; this may frequently 

 be traced to one of the extremities of the body, and sometimes 

 it gives off another branch ; ultimately the canals become so 

 excessively fine, that they are invisible. Their opening into the 

 vesicle and their course in running from it are seen very di- 

 stinctly when the contractile vesicle is turned directly upwards ; 

 we may then recognize how the canals run between the con- 

 tractile reservoirs, which lie very close to the surface of the body, 

 and between the surfaces of the body inside the cortical sub- 

 stance ; and the orifices may likewise be seen. Another re- 

 markable position is when the nucleus is turned next the observer 

 at the surface of the body ; the canals are then seen remarkably 

 clearly on its bright background. A few canals always run 

 over directly, with a slight curvature, towards the posterior part 

 of the mouth. AVhcn the animalcule lies so that the contractile 

 vesicle appears at the margin of the body, there is sometimes an 

 appearance as if one or more of the canals opened externally at 

 this point ; but close examination shows that they curve round 

 and run towards other ])arts of the body. 



The number of vessels opening into the contractile vesicle in 

 Bursaria flava is about thirty ; this number, or a few more or 

 less, existed in all the specimens which I examined in reference 

 to this point. They are apparently uniformly distributed over 

 the whole surface. 



The specimens of Bursaria flava with two contractile vesicles 

 have the system of canals double, each system grouped inde- 

 pendently around its reservoir. The canals of the posterior 

 reservoir stretch into the district of the anterior; but I have 

 never been able to detect any communication between the two. 

 In the Ojjhrijog/e/ia from the Spree, very little could be detected 

 of the canals, even when the interior of the body contained only 

 slightly refractive substances. AVhen a suitable specimen is 

 somewhat compressed between the glasses, so that it cannot 

 move about, the vessels are especially seen when they have the 

 nucleus for a background, and when they end in the contractile 

 vesicle. 



I have never been able to trace any vessels into the interior of 

 the body ; for instance, towards the nucleus. I am also ignorant 



