MECZNIKOW, ON THE VORTICELLA-STEM. 287 
A weak induction-current has no effect on the Vorticellz ;* 
but when the force of the current is increased up to a certain 
point, its passage through the preparation caused the instan- 
taneous contraction of all the stems; but even when the 
current was maintained for some time, this position was not 
long retained. The animalcule soon stretched itself out 
again, and began its movements afresh. The force of the 
current may now be increased considerably without any 
change in the phenomena. But if a very powerful current 
is applied, the Vorticellz, it is true, roll themselves up, but 
they die almost immediately, as is shown by the circumstance 
that on the breaking of the current the animalcules remain 
perfectly still; and if the same strong current is kept up for 
any length of time, the Vorticelle break up, as Kuhne very 
truly states. It is to be remarked, moreover, that whilst 
under the influence of the galvanic current, the anterior 
ciliary apparatus always remains retracted, as stated by 
Kiuhne. 
2. Rhodankalium, a substance which, as is well known, 
produces powerful contractions and sudden rigidity in muscle, 
does not, from what the author has observed, even in a 
tolerably concentrated solution (0°3 grm. to 5 cc. water), pro- 
duce any effect whatever on the movement of the stem of 
Vorticella; nor are weaker solutions (0°3 grm. Rhodanka- 
lim to 10, 15, 20 cub. cent. water) any more efficacious. It is 
certainly very interesting to observe the length of time the 
Vorticellze can live in these solutions, since all other Infu- 
soria observed by the author, even the lowest (Monas), die 
very speedily in them. But the Vorticellze, even after their 
body has become quite deformed and angular by the action 
of the solution, nevertheless still continue to move. This 
observation was several times repeated by the author, and 
always with the same result, although it is in direct contra- 
diction to Kiihne’s assertion, that the stem of Vorticell 
contracts and becomes rigid in a solution of Rhodankalium. 
8. Veratrine.—It is usually stated that Veratrine is in- 
soluble in either cold or hot water, but this is not correct. 
The author boiled, five times in succession, the same quan-: 
tity of Veratrine in distilled water, and the filtrate on each 
occasion assumed a carmine-red colour on the addition of 
concentrated sulphuric acid. 
It is well known that Veratrine is a very powerful muscular 
poison, inducing very speedy contractions and rigidity. A 
* The species employed in all the experiments were /”. convallaria, Ehr., 
and /’, microstoma. 
