54 THE MICROSCOPE. April 
In addition to making out the general form of the 
animal, one is apt to find many peculiar short rounded 
bodies (fig. 1, go.) which in some species are grown in 
grape like clusters. These are the reproductive organs 
and have an especial interest, because many hydroids have 
an alternation of generations so that these little bodies 
are not hydroid eggs as we might suppose, but are 
minute jelly fish, some of which, if you let the material 
stand over night, will escape; and if one looks sharply 
for them they can be seen travelling gracefully to and 
fro in the water. The accompanying cuts (figs. 4 and 5) 
represent somewhat their appearance before and after: 
their liberation. 
Many forms however, instead of liberating these 
medusa forms, seem sure enough, to produce eggs and 
spermatozoa, as we might think the more natural. The 
meduse are essentially produced but have through 
degeneration lost their power of movement. Figures 2 
and 3 will indicate the principal difference between these 
male and female gonophores. . Those producing eggs 
will often be much distorted by the growth of the eggs, 
for they undergo quite a development before they are 
liberated. The sperm producing buds are quite char- 
acteristic, because of being more or less clear and to a 
low power homogeneous, with a dark central stalk divid- 
ing them into two divisions. 
The careful study of the development of the eggs is 
not hard to carry on, and will more than repay for the 
time given it. Should it not be desirable to watch the 
changes in any particular cell, one can by comparing a 
number of buds, soon get an idea of the entire process 
PRESERVATION.—The fixing agents which will best kil] 
the tubularia with tentacles expanded are Perenyis’ fluid, 
picro-sulphuric acid or a saturated solution of corrosive 
sublimate. They should be quietly but quickly lifted 
from the water into the killing fluid, allowed to stay in 
