OF DENISON UNIVERSITY. 
131 
MISCELLANEOUS NOTES. 
A Note on a Peculiar Habit of Fresh Water Hydra. 
During the last of September, while examining, in the laboratory, 
an aquarium containing Hydrodictyon, Spirogyra and other plants, 
I noticed on the sides of the aquarium a few Hydras and, as the class 
in Zoology would need some for study about the last of NoYember, I 
placed the vessel in a window and renewed the water from time to 
time and soon noticed that the Hydras were reproducing by budding 
very rapidly. As the time approached for the class to need them, 
there was quite a large number, with buds in all stages of development. 
But, greatly to my surprise, in a day or two afterwards, when I 
went to the aquarium to get specimens for the class, there was not a 
single Hydra to be seen on the sides of the aquarium, where they had 
been so abundant. My first thought was that some one had disturbed 
them, but upon accidentally turning over a piece of bark that happen- 
ed to be in the bottom of the glass, I found underneath it all the ani- 
mals that had but two days before been attached to the sides of the 
receptacle. 
Upon examination, I found that, without exception, they were 
all reproducing by means of eggs. The large ovaries, and testes, 
producing spermatozoa with two flagella, forming from the ectoderm 
in numbers as high as six on a single animal. By placing some of 
these animals in the light they again began reproducing by budding. 
Thus showing by a few simple experiments that the most common 
method of reproduction, by budding, takes place in the light, but when 
the animal reproduces by means of eggs it seeks the dark and be- 
comes quite inactive. A fall in the temperature of the room might 
account for the sudden change observed, in this case, in the method 
of reproduction. The eggs, covered with a thick chitinous shell, fall- 
ing to the bottom, pass the cold months in that state. Both forms of 
Hydra vulgaris, H. virdis and the one under cosideration, H. fusca, 
are quite common in this locality. 
A more extended discussion of the Hydra may appear in a future 
issue of the Bulletin. 
W. G. Tight. 
