MECZNIKOW, ON THE VORTICELLA-STEM. 289 
The stem, in fact, even when the body of the Vorticella is 
wholly contracted and wrinkled, still exhibits movements. 
9. Caustic potass—The sudden application of a solution of 
potass containing not more than one part in a_ hundred 
instantly kills all Infusoria; its more gradual application is 
followed by less rapid decease. It has no effect whatever on 
the stem of Vorticella, although in muscle it produces con- 
tractions. 
10. Curara.—With respect to this substance the author 
fully confirms, from long-continued observation of his own, 
Kihne’s statement that it has no effect on the stem of Vor- 
ticellee. This fact appears the more interesting when we find 
that the poison is not without influence upon the body of the 
animal, as may be seen in the circumstance that the anterior 
ciliary apparatus always remains retracted under it. 
When the action of the various reagents employed by the 
author is considered, it must be allowed, he says, that, at any 
rate, we have no right at once to identify the mobile element 
in the Vorticella-stem with a muscle, as many have done; 
and this view is the further supported by the fact that the 
stem presents no property of double refraction in polarized 
light, as repeated observations have shown. He, more- 
over, takes the opportunity of remarking that he was as unable 
as was Kiihne to confirm Leydig’s statement respecting the 
transverse striation of the stem. ‘When it is examined,” he 
says, “with a power of 1000 diameters (Ocular No. 4, and 
system No. 9, 4 immersion, of Hartnack) no doubt can be 
entertained as to its homogeneity and as to the non-existence 
of transverse striation.” 
