M. N. Lieberkuhn on the Anatomy of the Infusoria. 325 



at present whether that part of the contractile vesicle which is 

 turned toward the centre of the body of the animalcule receives 

 any vessels. 



Both Bursaria flava and Ophnjoglena flavicans belong to those 

 Infusoria in which the contractile reservoirs may assume the 

 well-known stellate form. Von Siebold describes this phseno- 

 menon, in Paramecium, in the following words : — *^ These pul- 

 sating spaces have a very striking shape ; they consist of two 

 central round cavities, around which stand from five to seven 

 smaller pear-shaped reservoirs, with points directed outwards, 

 in the shape of a star. In the pulsation of these strange star- 

 shaped reservoirs sometimes the stars disappear entirely, some- 

 times only the central round spaces, and sometimes only the 

 rays." The opake Bursaria exhibit this phsenomenon just in 

 the same way as it is described by Von Siebold; and those 

 specimens in which the vascular system can be detected, ojffer 

 the explanation of it. The small pear-shaped spaces are really 

 the commencements of the vessels, which expand with the 

 accumulated fluid, and the rays are the further prolongations of 

 the same, which may be traced to the ends of the body. 



At the moment when the contractile vesicle has attained the 

 greatest expansion, that is, when the diastole is terminated, it 

 appears in the form of a globe filled with colourless fluid, from 

 which the vessels run out on all sides in the cortical substance 

 as canals, apparently of equal diameter ; they have at this time 

 the smallest diameter they can assume at their embouchure into 

 the reservoir. In opake specimens, this is the moment when 

 the opened contractile vesicle is observed. A little before we 

 observe the commencement of the systole, the vessels begin to 

 expand slowly, at points distant about one diameter of the con- 

 tractile vesicle from the surface of the latter, to many times their 

 original size. The more the systole progresses, the wider and 

 longer become the swollen places, and they approach gradually 

 to the contractile vesicle. If we make an observation at the 

 moment when the diameter of the contractile vesicle is diminished 

 to about one-fourth of its original size, the shape of the apparatus 

 agrees in all essential points with the well-known stellate figure, 

 represented by Dujardin in Paramecium Aurelia, with the single 

 exception that the embouchures of the rays are distinctly visible, 

 and their peripheral prolongations run out widely in the form 

 of canals over the entire animalcule. Opake specimens of the 

 Bursaria display the phsenomenon only in such a degree that the 

 rays terminate in delicate attenuated points, at a distance of 

 about one diameter of the reservoir from the latter. When the 

 contractile vesicle has closed completely, the fusiform ly expanded 

 vessels only are seen, as they run together with their apices to 



