286 MECZNIKOW, ON THE VORTICELLA-STEM. 
over, points out a special connection between the shortening 
and extension of the stem and the motions of the ciliary 
apparatus, which is retracted on the shortening, and protruded 
on the extension of the stem. Czermak* showed that the 
streak itself was spiral, and that the shortening, of the stem 
was effected by it. Leydig + even describes transverse lines 
on the central streak of the Vorticelle—an appearance which 
is regarded by him as a strong proof against the theory of 
unicellular organisms. Claparéde and Lachmann{ fully 
agree with Czermak, and assert, besides, that the central 
streak when retracted is lost sight of in the hinder part of 
the body. 
Among the opponents of this view may be named Dujardin, 
Ecker, and Stein. The first thinks that the movements of 
the stem do not depend upon the enclosed band, but upon 
the external membrane ; but this was completely and correctly 
disproved by Eckhardt. Ecker thus expresses himself re- 
specting the nature of the stem: ‘ The contractile substance 
of the body is continued into the stem, the form of which 
part it consequently follows, but this band-like portion is 
nevertheless not a muscle.”’ Stein,§ however, is the most 
determined opponent of Ehrenberg’s view. ‘This observer 
denies the existence of transverse lines on the central band, 
which were first described by Gleichen and afterwards by 
Ehrenberg. Besides this, Stein subjected the Vorticelle to 
the action of various substances, and found that the central 
band exhibited the same reactions towards them as the in- 
ternal parenchyma of the body itself; he thence concludes 
that the stem is not identical with muscular tissue. 
This was the state of the question before the publication 
of Kiihne’s || researches, by which this author was led to the 
same conclusion as Ehrenberg and his followers. Kiihne 
compared the effects of various physical and chemical re- 
agents on the muscles of the frog and on the stem of Vorticelle, 
and found them to be essentially the same in both cases. 
The author having instituted some researches according to 
Kiihne’s method, is desirous of communicating them, inas- 
much as the results at which he has arrived differ widely 
from those of Kiihne. 
1. Electricity—The phenomena observed were as follows : 
* ¢ Zeitsch. f. wiss. Zool.,’ iv, p. 438. 
tT * Lehrb. d. Histologie,’ 1857, p. 133. 
t ‘ Zeitsch. f. wiss. Zool.,’ i, p. 236 (note), 
§ ‘Die Infusionsthiere,’ 1854, pp. 78—S0; and ‘Der Organismus der 
Infusionsthiere, 1859, p. 54. 
|| ‘ Myologische Untersuchungen,’ 1860, p. 213—222. 
