386 Dr. R. Greef on the Structure and 



In the preceding section we have endeavoured to prove that 

 the external coverings of the body which enclose the interior 

 space consist of three different parts, namely the external cuti- 

 cula, the muscles lying beneath this, and the cortical layer 

 following upon these. Although with respect to what in the 

 Vorticellffi and the Infusoria in general is to be regarded as 

 cuticula or as muscles, and with respect to the relations of 

 these two parts, we have been compelled to express opinions 

 in some points at variance with those of Stein, we are never- 

 theless in general in agreement with him in regard to the 

 actual existence of the cuticula and muscular fibres as separate 

 parts. We have here therefore to do chiefly with the exist- 

 ence and interpretation of the cortical layer ^ especially in its 

 relations to the interior space and its contents. 



If we examine a living Vorticellan carefully and for a long 

 time (for Avhich purpose, of course, the species of Ejnstylis are 

 best adapted, as with them we are not disturbed in observation, 

 as with the contractile-stalked Vorticellans, by constantly re- 

 peated and sudden contractions causing the continual disap- 

 pearance of the object), one of the most remarkable of pheno- 

 mena very soon strikes us — namely, that apparently the whole 

 mass of the contents of the body is engaged in constant rotatory 

 movement. This is the rotation-current first observed by Focke 

 and then by others in Paramecium and other Infusoria, and 

 also by Lachmann in the Vorticell^e, which must so far be re- 

 garded as a discovery of importance, that it furnishes us with 

 the clearest evidence against the nutritive apparatus ascribed 

 by Ehrenberg to the Infusoria. The actuality of this rotation- 

 current itself cannot be doubted - it is one of the constant and 

 normal vital manifestations of the Infusoria in question. It is by 

 no means, as Ehrenberg endeavours to establish for the further 

 support of his system, a pathological phenomenon produced by 

 pressure, displacement of the contents, &c. It is observed 

 under all circumstances in the living animal, even when not 

 the smallest altering influence, such as pressure &c., exists ; 

 and it may be most easily and distinctly recognized when the 

 contents of the body are coloured, or when for this purpose a 

 colour-diet (carmine) has been administered to the animals. 



Ejyistylis jlavicans ^ which has already repeatedly been re- 

 ferred to, is one of those species of Ejnstylis which are gene- 

 rally more or less intensely coloured yellow or yellowish brown 

 by nature, and also one of the larger species ; and in it, for 

 other reasons also, the phenomenon now under discussion may 

 be very well followed in all its details, for which reason, in 

 what follows, we shall chiefly take it as the foundation of our 

 observations. If we carefully examine the movement of rota- 



