374 Tue MIcROScOPE. 
cane under my arm, I am fully equipped to operate on any pond © 
or swamp that may come in sight. Like the modern bullet my 
outfit is small, but wonderfully effective. And not the least ad- 
vantage is that the cost is a mere cipher, a fact to commend itself 
to all. 
If the bolting silk should not retain the finer forms, make a 
small bag of cambric handkerchief, slip it over the bottom 
of the can and tie in place with a rubber or other band. The 
Diatoms, Desmids, et cetera, will pass through the silk and be 
caught by the bag, whence they may be washed. 
To use this simple but most effective implement for the col-. 
lection of surface forms when in a boat, a small curtain-ring may 
be fastened on each side, with a cord passed through each, up. 
over the lid and so connected with the fishing rod or line. 
AN OBSERVATION ON THE COMMON HYDRA. 
H. E. VALENTINE. 
\ | OTICING some unusually fine specimens of Hydra (H. fusca) 
attached to the sides of my winter jar, a few days ago, I 
secured one and placed it on the stage of the microscope. My 
attention was immediately attracted to two swellings of the ecto- 
derm just below the tentacles. The unbroken line of the body 
was visible through these elevations, there being apparently no 
connection between them and the interior. 
The next evening I had the same animal under observation,. 
but there was a marked change in the appearance of the protu- 
berances. Both had very materially increased in size, and in- 
stead of the smooth convex surface seen before, each was sur- 
mounted by a kind of knob in which an active circulation was 
going on. The enclosed space was crowded with particles simi- 
lar in appearance to the granules usually seen in the vacuoles of 
a Closterium. This movement was also apparent in the main 
portion of one of the protuberances, although later it became 
confined to one margin. Among the particles in one of the knobs 
were two thread capsules which were being turned and twisted 
about in a very lively fashion. 
The cuticular covering of one of the swellings was finally rup- 
tured, and the contents were scattered over the slide. There was 
a slight oscillatory movement among some of the freed particles, 
