288 MECZNIKOW, ON THE VORTICELLA-STEM. 
frog, into which a filtered, very bitter decoction of Veratrine 
had been injected, soon died. Nothing of the kind takes 
place when Infusoria are exposed to the same solution, 
and numerous experiments have satisfied the author that 
this poisonous agent has no effect whatever upon the life of 
Infusoria. The stem of Vorticellze moves just as actively in 
a solution of Veratrine as before its immersion, and the 
whole behaviour of the animal presents nothing abnormal. 
Kiihne describes the action of this poison quite otherwise. 
He states that the Vorticelle are killed by it, and that the 
stem contracts and becomes rigid—statements which the 
author has been wholly unable to confirm. 
4.. Hydrochloric acid.—According to Kiihne, a solution of 
this acid containing ;1,th part induces speedy coutractions 
and rigidity in the stem, succeeded by its solution. But 
this statement the author is not able to confirm any more 
than he is the preceding. In his experiments he employed 
a solution of the same strength as that used by Kiihne, and 
observed the following results:—At first the stem is moved 
with some rapidity ; but the movement gradually becomes 
slower and slower, and at last ceases altogether. The same 
phenomena are manifested also when much stronger solutions 
are employed (3 drops in 5—10 cub. cent. of water). 
5. Common salt.—Concentrated solutions of this salt im- 
mediately kill all Infusoria; weaker ones act less energetically, 
the Infusoria dying more slowly. A solution containing half 
part of salt per cent. had no effect whatever upon the stem. 
6. Chromic acid.—<According to Kiihne, this acid causes 
muscle to contract. In the stem of Vorticelle, a solution 
containing two parts in the hundred causes sudden contrac- 
tion, and extension never again takes place, although the 
body of the Vorticella continues to live. This contraction, 
however, cannot be attributed to the property possessed by 
chromic acid of coagulating albumen, since other substances 
possessing the same property (alcohol, acetate of lead) have 
not the same effect. 
7. Bile.—The sudden application of bile kills and dissolves 
all Infusoria; whilst a slower one allows them to die more 
slowly. But bile has no irritant effect upon the stem of 
Vorticella, although in the frog’s muscle its application is 
followed by contraction and shrivelling up.* Diluted bile 
has no effect whatever on the movements of the stem. 
8. Sulphate of copper.—Solutions of this salt of any strength 
cause the most powerful contraction in muscle; but im the 
stem of Vorticellee even concentrated solutions have no effect. 
* Kihne, op. cit., p. 24. 
