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



other very much in form and in the structure of the mouth ; 

 Ehrenberg himself, too, has said, that he only distinguished 

 Ophryoglena flavican^ from a Bursaria by its eye-spot. Bursaria 

 flava, which I found in great numbers, in spring and summer, 

 in stagnant water in the Berlin Thiergarten, has the same 

 structure of the mouth, the same throat-like prolongation, and 

 the same undulating membrane as Ophryoglena flavicans ] the 

 watch-glass-shaped organ also stands in the same place, near 

 the concave side of the mouth, and likewise regularly has its 

 convexity directed towards the point of the head; the only 

 difference is a slightly larger size, the diameter of the base 

 amounting to y^^^-ths of a millimetre, when the animalcule did 

 not exceed i of a millimetre in length. In the interior of the 

 body frequently occur long, yellow-ochre- coloured globular gra- 

 nules, about y^^th of a millimetre in diameter, rendering the ani- 

 malcule opake ; among these were isolated colourless spheroidal 

 cavities, like those which Ehrenberg describes in Bursaria flava, 

 I could not find an anal orifice ; but sometimes there was at the 

 posterior extremity of the body a light spot and a depression, 

 which Ehrenberg refers to the anal orifice. I found the form of 

 the body to agree exactly with that of Bursaria flava as figured 

 by Ehrenberg, as did also the position of the contractile vesicle ; 

 so that Ehrenberg^s description exactly applied : " Bu7'saria 

 corpore ovato-oblongo, flavo, ssepe postica parte pauUo tenuiore, 

 subacuto, ore corporis aliqua parte superato.'^ ■.iommb .1;^s3i>oi^ 

 Let us now return to the description of the nucleolus in 

 Ophryoglena flavicans. As this animalcule usually contains in its 

 interior extremely few, and at the same time minute granules 

 of strong refractive power (in rare cases I found them like those 

 which occur in Bursaria flava), the internal structures are 

 generally readily perceived. The nucleolus is shaped like a 

 grain of barley, and is marked at each end with a few sharply 

 defined streaks or furrows ; its length is somewhat more than 

 y^^ths of a millimetre, its thickness in the middle about y^(yth 

 of a millimetre. Its substance has a stronger refractive power 

 than that of the rest of the body, but far less than the fat-like 

 globules. Under the highest magnifying power, no structure 

 could be distinguished; and it withstands for a considerable 

 time the action of water. The nucleolus is situated on the 

 middle of the testis, as Ehrenberg called this organ, or the 

 nucleus, as it is termed by Von Siebold. The nucleus is about 

 one-fifth of the entire length of the animalcule, and its breadth 

 in the middle is about one-third of its length. Its longitudinal 

 axis ordinarily coincides nearly, like that of the nucleolus, with 

 the long axis of the animalcule. It is of ovate form; its sub*- 

 stance displays no recognizable structure. vtvs^TMS 



