TRANSLATIONS. 
The Laws of the MovEMENTs in Microscopical PLants and 
Animas whilst under the INruvuENcE of Licur. By 
Professor F. Conn. 
(Translated from a German pamphlet sent by Dr. Cohn.) 
By microscopical animals Professor Cohn means only the 
Infusoria, and especially those mouthless genera of Infusoria 
which are provided with cilia. Those which are provided 
with mouths (Stomatoda of Siebold) bear in their definite 
motions, which are correlated with their taking up solid 
nourishment, a marked differentiating character. By micro- 
scopical plants only those genera are understood which are 
possessed of an independent power of migration, or of a de- 
velopmental condition in which this is the case. Both classes 
taken together are to be termed merely ‘ microscopical 
organisms.” 
In the researches, of which this is a summary, the question 
as to the primary cause of the movement, or the moving 
power, is not in any way at issue. Of whatever kind the 
power may be that puts a body in motion, it is easily seen 
that this movement may be made in every possible direction. 
If microscopical organisms exhibit in their movement a defi- 
nite direction, then there must be some special cause which 
appoints the direction of the movement. ‘This cause of the 
direction of the movements is light. 
In colourless microscopical organisms Jight has no influ- 
ence, and no appointed direction of movement is to be ob- 
served; these organisms appear to move in every possible 
direction. 
In Diatoms and Oscillaria, one of which contains a brown 
(pheophyll) and the other a greenish colouring (phyco- 
chrome) matter, the influence of the light makes itself so far 
appreciable that they prefer the light to the dark, and there- 
fore seek the surface in large numbers. A further influence 
upon the direction of their movements has not yet been 
shown. Upon an equally lighted surface the Oscillaria 
develop radially on every side from the dark central en- 
tanglement of threads, and grow equally over every side of 
