372 
The Reactions of Hydra to the Electric Our- 
rent: RAYMOND PEARL. 
An expanded hydra with the long axis 
of the body at right angles to the direction 
of the current becomes oriented with the 
head towards the anode shortly after the 
current is made. This orientation is 
brought about by a contraction at a point 
just above the foot on the anode side of the 
body. The bending of the body at this 
point is very slow, but continues until the 
long axis is parallel to the direction of the 
current and the head is towards the anode, 
i. e., until the Hydra is oriented. The de- 
tails in the mechanism of this orientation 
are modified with increasing intensity of 
current, but the essential factor, namely, 
contraction on the anode side, is constant 
except when the very strongest currents 
are used. On making a current of such 
strength as practically to kill the hydra, 
immediately there occurs a slight muscular 
spasm on the kathode side of the body. If 
at the timeof making the long axis of the 
body is already parallel to the direction of 
the current and the head is towards the 
anode, the animal contracts immediately 
and violently, while in the opposite position 
there is no immediate contraction. The 
e mtraction phenomena of the tentacles are 
different from those of the body as a whole. 
The Effect of some Climatic Factors upon the 
Oolor and Color-patterns of Insects: W. L. 
TOWER. 
The effect upon variations of color and 
color patterns of the environmental factors, 
temperature, moisture, food and light has 
been investigated experimentally during the 
past two years. Coleoptera and Lepidop- 
tera have been used and have been sub- 
jected to the conditions of the experiments 
throughout the life cycle. The results rep- 
resent more nearly the effects these factors 
produce as they act in nature, than when 
applied at one stage alone, @. e., pupal. 
SCLENCE. 
[N. S. Vou. XIII. No. 323. 
The most extensive work has been done 
with Leptinotarra decem-lineata Say, and 
these results will be published soon. 
Additional Remarks on Cave Salamanders: C. 
H. EreenmMann. J 
The types of a new cave salamander from 
Missouri were exhibited, also a specimen of 
the bleached cave salamader, Typhlotriton 
from Marble Cave, Mo. The latter had 
been kept in the light for a few weeks and 
showed a marked increase of pigment in 
its chromatophores. The amount of bleach- 
ing in cave animals is directly proportional 
to the degree of degeneration reached by 
the eye. Whether there is any connection 
between the two is under investigation. 
Epigean species, if living in caves for any 
length of time, become bleached. The 
presence or absence of color is, then, due in 
the first instance to the environment. The 
cave fishes of Indiana no longer respond to 
the change in their environment, as the 
salamander does, and even the young of 
the cave fishes, if reared in the light, do 
not take on color. The bleached condition 
has become hereditary in their character. 
In the establishment of the bleached condi- 
tion, which in the first case is an individu- 
ally acquired character in the hereditary 
mechanism, we have an instance of the 
transmission of the direct effect of environ- 
menb. : 
The Relation between Base-leveling and Plant 
Distribution: Hexry C. Cow es. 
The local distribution of plants depends 
largely upon the character of the topog- 
raphy. The topography constantly under- 
goes well-known changes, hence the vege- 
tation must change. In other words the 
ecological study of plants and plant societies 
should be based on dynamical principles. 
The growth of a river well illustrates these 
principles ; first, there is a xerophytic gully, 
then a ravine, whose slopes soon become 
mesophytic. As the valley widens the 
