OF THE PKOTOZOA. CILIATA. 325 



iinable to discover that the contents of the contractile vesicle were expelled 

 externally in the systole. Actinophrys is better suited to the settlement 

 of this question than a ciliated Infusorium. I have many times sought for 

 currents in the fluid siuTounding Actinophrys Sol and A. Ekhhorn'ii, when the 

 fluid contained masses of fine globules immediately in front of the projection 

 of the contractile reservoir ; but I have never seen, any more than Claparede, 

 any corresponding displacement when the vesicle contracted. In Bursaria 

 leucas, B. Vorticella, Paramecium Aurelia, and P. Chrysalis, I obtained the 

 foUo^ving results : — The contraction takes place exactly in the manner de- 

 scribed by Schmidt ; the vesicle contracts from the interior of the animalcule 

 towards a point Ij^ng near the surface, and it expands on the entrance of the 

 fluid in such a manner that it increases in diameter gradually from the surface 

 of the animacule inwards toward the centre. But does this teach us what 

 Schmidt concludes from it, that the reservoir expels its contents outwardly 

 every time when it contracts toward the outside, and becomes filled from without 

 when it expands toward the interior ? If the contractile reservoir is attached 

 by that part turned toward the surface of the animalcule to the internal surface 

 of the cortical substance, while the portion projecting into the interior of the 

 body is free in the soft medullary mass, will not the contraction take place 

 from within outwardly, and the expansion from without inward, whether the 

 fluid flow inwards or outwards ? In Actinophrys, sometimes in Arcella vul- 

 garis, and in Urostyla granclis, a totally different import must be attributed 

 to the contractile reservoii', if Schmidt's criterion be valid ; for here the re- 

 servoir does not contract toward the surface, but toward the interior of the 

 body, and forms an elevation on the surface when it becomes filled, as de- 

 scribed minutely in Actinophrys by both Yon Siebold and Claparede. But 

 it is not on this alone that Schmidt rests his opinion : he asserts that he has 

 observed also an actual external orifice of the contractile vesicle. I must 

 admit that Bursaria Vorticella has a distinct orifice at the hinder part of the 

 body, and this exactly at the place to which the contractile vesicle contracts 

 until it vanishes. But regarding this orifice which I saw, only so much is 

 established — that it is the anal orifice which Ehrenberg has already described. 

 I have seen the emergence of remains of devoured substances, of loricae of 

 Bacillaria, of fine undeterminable granules, &c., from this very hole, so fre- 

 quently, that there can be no doubt on this point ; and it is even not rare for 

 a corpuscle to slip out from the anal orifice during the diastole, — that is to 

 say, at the very time when, according to Schmidt, the fluid should flow in 

 from the outside. I found the Bursaria just named during spring and sum- 

 mer in standing water near Tempelhof ; it agrees in the main with Ehren- 

 berg's Bursaria Vorticella. The buccal orifice is situated as in Bursaria 

 truncatella, in which, however, I did not observe any contractile vesicle at 

 the posterior end of the body. The specimens of B. truncatella I observed 

 were aU about ^ of a line or more long, those of B. Vorticella at most ^ 

 of a line. The latter is in any case not a Leucophrys ; therefore, in case 

 Ehrenberg considers his Bursaria Vorticella a Leucophrys, it is a different 

 animalcule from the latter. I was equally unable to satisfy myself of the 

 correctness of Schmidt's view in the Paramecia. When a specimen of Para- 

 mecium Aurelia lies so that the contractile vesicle, either the anterior or pos- 

 terior, is seen at the margin, it appears, under certain circumstances, as though 

 a short canal ran directly out through the integument of the animalcule ; 

 but in reality it only runs into the integument, and tiu^ns round toward the 

 side of the body directed away from the eye : I found the same in Parame- 

 cium Chrysalis also : it was always one of the rays of the contractile vesicle 

 which presented to Schmidt the appearance of an external oiifice. The same 



