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



Focke, P. Aurelia, P. caudatum, and Bursaria leucas^), there are 

 fusiform rods in the cortical layer, from which Allman states 

 he has seen urticating filaments projectedf. In the Vorticella 

 we shall hereafter have to describe in the cortical layer a 

 contractile layer as the continuation of the muscle of the stem. 

 We cannot certainly regard a part so complicated as the mem- 

 brane of a cell ; I believe that this " cortical layer " (of Cohn) 

 is rather to be considered as the parenchyma of the body 

 of the Infusoria, whilst the rotating mass only constitutes the 

 contents of a large digestive cavity or stomach, and therefore 

 must be regarded as chyme, and that Cohn's " cuticula " forms 

 the true skin of the Infusoria. 



The " cortical layer '' alone is contractile : in torn Infusoria 

 fragments of it not unfrequently contract, whilst the internal 

 mass, the chyme, which flows out, never does this. When an 

 Infusorium is sucked out by an Acineta, the cortical layer or 

 parenchyma of the body may often contract for a long time, and 

 the contractile vesicle placed in it may also continue its contrac- 

 tions for hours; nay, I have observed a Sti/lonychia, which, 

 although a considerable part of its chyme had been sucked out 

 of it by an Acineta, still underwent division, so that one of the 

 gemmules of division swam away from it briskly, and only the 

 other half of the old animal was destroyed. This appears also 

 to a certain extent to prove that the mass sucked out does not 

 represent the true parenchyma of the body, and as it only fills 

 the large cavity of the body in the form of a tenacious fluid 

 mass, and becomes mixed with the nutritive matters, especially 

 when no small masses are formed, it is certainly the most natu- 

 ral course to regard it as chyme. It cannot be urged against 

 this view, that in those Infusoria which contain chlorophyll- 

 corpuscles in the substance of their bodies, we sometimes meet 

 with single corpuscles in the rotating mass, as they may certainly 

 be easily loosened from the parenchyma, and thus get into the 

 chyme-mass. The nucleus, indeed, projects into the chyme- 

 mass; but as a general rule, it appears to be affixed to the 

 parenchyma of the body, as we do not see it rotate with the 

 chyme-mass J : in Opercularia berberina, Stein sometimes saw 



* See O. Schmidt, 1849, p. 6. 



t Similar, but much thicker corpuscles, which presented a deceptive re- 

 semblance to the urticating organs of the Campanularioe, were found by me 

 and my friend, E. Claparede, in an animal living as a parasite upon Cam- 

 panularice, which is probably to be referred to the Acinetince, and which 

 we shall take another opportunity of describing. In the oval embryos, 

 ciliated on one side, which were squeezed out of the body of the mother, 

 we were enabled to convince ourselves that these corpuscles were enclosed 

 from two to nine together in a roundish proper vesicle (cell?). 



X When it divides, as is usually the case in the development of embryos 



