we 
978 THE AMERICAN NATURALIST. [VoL. XXXIV. 
knowledge in regard to the action of the constant electric current on 
lower organisms. The work bears evidence of having been carefully 
and well done. The first of the two papers is principally given to a 
description of the electrotactic reactions of Volvox, introduced by a 
brief account of the normal movements of the animals based largely 
on the results of Klein and Rösel. He finds the sense of the re- 
sponse to the current to be kathodic immediately after the circuit 
is completed. After the current has been passing for some time, 
however, this kathodic response becomes less and less evident, until 
finally there ensues a more or less distinct anodic movement; but 
this latter never becomes so well marked as the previous motion 
towards the kathode. If the Volvox is placed in a thin gelatine 
solution, so that it remains alive but is unable to move, very strik- 
ing changes in the form of the body accompany the action of the 
current. The anode side of the colony becomes wrinkled and 
crumpled together, while the kathode side is correspondingly swollen 
out. These phenomena become more apparent the longer the cur- 
rent acts, and take place without relation to the orientation of the 
axis of the body with reference to the current direction. At the 
same time all the parthenogonidia move towards the anode side of 
the colony. This movement is evidently an entirely passive one, since 
it occurs regularly in all stages of their development, as well before 
they are able to move actively as after. That the change in body 
form is of a purely passive character is evidenced by the fact that it 
takes place in the same way in colonies which have been killed in 
formalin. To extend the results the effect of the current was tried 
on lifeless individuals of Paramecium aurelia and bursaria, Colpidium 
colpoda, and Amcebe of different species, and in all these cases there 
resulted the anode crumpling and the kathode swelling. In his 
theoretical discussion Carlgren advances the view that the effect of 
the current on organisms is to a certain extent of a purely physical 
nature. He believes that this physical action is of extreme impor- 
tance, but does not attempt to make it account for all the facts. His 
results make it evident that in any future work on the subject this 
factor must at least be considered. 
In the second paper there is a detailed account of the electrotactic 
response of the larvae and embryos of a number of marine inverte- 
brates. "The point of greatest general interest is in regard to the 
reactions of the larve of certain echinoderms (Strongylocentrotus 
lividus, Spherechinus granularis, Ophiotrix fragilis, and Asteracan- 
thion glacialis). Young free-swimming stages of these animals gave 
