202 Dr. R. Greef on the Structure and 



In the first place^ notwithstanding many observations 

 directed to this point, I have been unable to convince myself 

 that the fine external transverse striation of the body already 

 repeatedly mentioned really has a spiral course. Stein, 

 indeed, seems only to have examined a single species as to this 

 point, namely Vorticella microstoma^ from which, perhaps not 

 without warrant, he deduces the same character for the other 

 Vorticellinaj which are furnished with strige. In this V. micro- 

 stoma^ however, he finds " a distinct spiral arrangement;" but 

 the ascent of the spiral is so small that the strige deviate 

 but little from the horizontal direction, and therefore produce 

 the impression of a simple transverse annulation. From this 

 admission, however, it seems to me to follow that the deci- 

 sion whether the strise in question have a spiral or an annular 

 arrangement cannot be made so easily as Stein's statements 

 would lead one to suppose. For my own part, at any rate, 

 I have hitherto not only been unable to detect the spiral 

 arrangement of these strise, but have always obtained only the 

 impression of a regular transverse annulation, even in those 

 forms in which the stri^ have comparatively broad interspaces 

 between them. In this inquiry I have chiefly directed my 

 attention to the course of the strise on the conical base of the 

 Vorticellan body and to the anterior margin, especially when 

 the rotatory organ was retracted into the interior of the body 

 and the peristome covered it like a sphincter. At these two 

 points, probably, it would be most easy to decide the question 

 by seeking to detect the commencement or the end of the 

 spiral line. But even here illusions may easily be produced, 

 in consequence of the state of contraction or the position of the 

 body at the moment. At any rate, as Stein himself admits, 

 the ascent of the spiral, if it exists, is extremely small ; so 

 that, especially when the strias are, besides, very fine, and fol- 

 low closely upon one another (as in Garchesium j^olypinum)^ 

 it can only be recognized with great difficulty by direct 

 observation. 



In the second place^ also, I have hitherto been unable 

 to convince myself that the transverse strise of the Vorticellae 

 now under consideration stand in direct relation to the mus- 

 cles, or rather, as Stein thinks, that these striae are the muscles 

 themselves ; and this leads us, leaving the Vorticellce out of 

 consideration for the present, to a short examination of the very 

 important question in our knowledge of the Infusoria, which 

 has already been touched upon, of the body-muscles of these 

 animals in general. This is the less to be dispensed with 

 here, as Stein obtained his results with regard to the muscular 

 strige chiefly by observations on other Infusoria {Stentor, 



