128 Dr. C. F. J. Lachmann on the Organization of Infusoria. 



Spirostomum ambiguum, aud some new animals which are to be 

 united with the Stentors in one family. In the former, the anus 

 is situated at the hinder end of the animal, and close in front 

 of it is the very large contractile vesicle ; when fully expanded 

 this vesicle appears to be surrounded only by a thin membrane, but 

 nevertheless we see balls of excrement, often several at the same 

 time, on different sides of the vesicle, separating the laminae of 

 its apparently simple covering, and forming projections which 

 are often nearly hemispherical both towards the vesicle and the 

 outer surface of the body. If masses of excrement do usually 

 penetrate through the parenchyma of the body, we should expect 

 it to be the case here when the tension of this is so great; we 

 should also expect to see the masses of excrement pass into the 

 contractile space if it were not a vesicle, but only a space in the 

 parenchyma without proper walls. Neither of these things 

 occurs, however ; the fsecal masses are not deposited from the 

 body until they have reached the anus at the hinder extremity 

 of the body. A similar strong expansion of a thin part of the 

 body by faecal masses, without any rupture, is seen, as already 

 mentioned, in some new Stentorina, which are distinguished 

 from the genus Stentor by their having that part of the paren- 

 chyma of the body which bears the ciliary spiral and the anus 

 (which in all the Stentorince lies on the dorsal surface of the 

 body close under the ciliary spiral (figs. 6, 7 & 8 e) and not in 

 a common pit with the mouth) drawn out into a thin process. 

 In one genus, of which I observed two species (one is the Vorti- 

 cella ampulla of O.F.Miiller) in company withE.Claparede on the 

 Norwegian coast, aud which I will describe elsewhere, this process 

 is broad and foliaceous, and bears the rows of cilia on the margin, 

 whilst the anus is placed far up on the dorsal surface of a thin 

 plate. In the other genus, Chatospira, Lachmann (figs. 6 & 7), 

 observed by me in fresh water near Berlin, the process is narrow 

 and bacillar ; the series of cilia commences at its free extremity, 

 and only forms a spiral when in action by the rolling-up of the 

 lamina; in this genus also the process bears the anus. In both, 

 frecal masses (as at m in fig. G) which are thicker than the pro- 

 cess in its extension, pass through it to the anus {e), without 

 breaking through it, notwithstanding the great expansion of its 

 walls. 



Not unfrequently, several balls of excrement unite into a large 

 mass before the anus, in order to be passed out together. When 

 an excretion takes place, the anus is seen to open (but often 

 closes once more and opens again before the expulsion of the 

 masses is effected), and then the fsecal masses are often expelled 

 slowly. 



[To be continued.] 



