Dr. C. F. J. Lachmann on the Organization of Infusoria, 127 



tlie nucleus moved a little out of its previous position by a mass 

 of food striking against it ; but as it soon returned again to its 

 position, this rather speaks for than against its attachment. In 

 different individuals of the same species, the nucleus does not 

 always occupy the same situation, — a circumstance which may 

 probably be explained by fissation, as in the transverse division 

 of an Infusorium, in which the simultaneously divided nucleus 

 lies about in the middle, one portion of the nucleus will be 

 situated in the posterior part of the anterior bud, whilst the 

 other part will occupy the anterior part of the posterior one. 



In many respects the parenchyma of the body of Infusoria 

 resembles that of the Turbellaria, in others that of the Polypes ; 

 they also approach the latter especially by the possession of a large 

 digestive cavity, in which, as in the Actinice, a tube (oesophagus), 

 open at the bottom, generally hangs down. Whether the wall 

 of this digestive cavity or stomach be one and the same with 

 the parenchyma of the body, or separate from this, cannot at 

 present be decided in most cases, although the former appears 

 to be the case : in Trachelius Ovum alone we see a proper sto- 

 mach-wall separated from the rest of the parenchyma by spaces 

 filled with fluid, and thus form an arborescent ramified canal, 

 which however must not be confounded with the nucleus*. 



The digestive cavity of the Infusoria (certainly at least that 

 of the cilated and some of the flagellated forms) possesses, besides 

 the mouth, a second orifice, the anus. This is certainly denied 

 by most of Ehrenberg's opponents, but a long and careful ob- 

 servation of an individual will always show that the fseces are 

 invariably thrown out at the same part of the body, and in many 

 Infusoria we may frequently recognise the anus in the form of a 

 small pit, on the surface of the animal, even for a considerable time 

 before and after an excretion ; (this is often the case in Parame- 

 cium Aurelia, P. Bursaria, Focke, diudi Stentor) . That the fseces are 

 not forced through the parenchyma at any point on the surface 

 of the body, is proved especially by the careful observation of 



(see below), individual fragments of iissation usually separate and rotate 

 with the chyme. When Siebold says (in his Comparative Anatomy, p. 24) 

 that he has often seen an Infusorium rotate round its nucleus, it is not 

 improbable that he has taken a rotating embryo (which, indeed, was not 

 known at that time) for the nucleus. 



* That this structure, described by Ehrenberg and disputed by others, 

 really exists, was affirmed to me by Dr. Lieberkiihn before I had the op- 

 portunity of investigating it closely myself; when I subsequently obtained 

 this abundantly, I was enabled to convince myself of the correctness of the 

 statement. The animals devoured {Trachelius Ovum is one of the most 

 voracious robbers) are always seen lying in the ramifications of the sto- 

 mach, in the clear spaces between them, except in crushed animals. The 

 clear round spaces in the parenchyma of the body are certainly no stomachs, 

 but contractile spaces. 



