DJ- DAPSNIA, AND 0? THE STEHCTTJEE OF THE EPHIPPITJM. 
81 
purpose of continuous watching, I kept by themselves in tumblers. For the purposes of 
observation, I used one of Smith and Beck’s ordinary glass cells, about -^o-th inch in 
thickness. This, being glued on to a glass shde, and a piece of thin glass placed over it, 
formed a cell, which held the Daplinia, and prevented it from moving, without doing it 
any injury. To put them into this cell I used a small metal tube, and in this manner I 
was able to watch the same specimen at intervals of a few hours, for several days 
together, and to observe gradually the formation of the eggs in the ovary, without doing 
any injury to my subject. To identify my specimens without fear of mistake, I placed in 
each tumbler a small bit of tinfoil, stamped with the number of the page in my note-book. 
Until now, “the male organs of generation have never been observed*,” and though 
Zenker f has described the testes of various species and the generative opening, he has 
placed and even figured the latter in probably the wrong place. Speaking of Sida cry- 
stallina^ he says, “ Sein Ausfiihrungsgang miindet an der den Fiissen zugekehrten Seite 
des Schwanzes auf. Diese Geschlechtsofihung variert nm* sehr wenig ihre Lage durch 
aUe Daphnoiden.” Either, however, the situation of the orifice in question does differ 
considerably in different species, or else he is certainly wrong in the place he assigns to it. 
If the tails of a male and female Baphnia (PI. VII. figs. 6 and 7) are compared, it will 
be at once seen that the papillae («) are much larger in the male than in the female. 
The vas deferens will almost always be seen leading to this point, and if a mature male 
be shghtly compressed, two clouds of minute bodies will be seen to come out in a stream, 
one from the papilla of each side of the body, and gradually diffuse themselves in the 
surrounding waters. 
To convince myself that these were really spermatozoa, on the 1 6th and 27th of 
June I compressed seven males, and altogether I must have examined about thirty, all 
with the same result. I then compressed seven females, and neither then nor at any 
other time could I observe anything similar in this sex. There can, therefore, be no 
doubt that these are the generative orifices, and that the minute bodies are the sperma- 
tozoa. 
These latter are rod-like bodies, about *0004 of an inch in length, and *000125 of an 
inch in breadth. They are almost stationary, but if closely watched, a slight wriggling 
movement can be observed, and several may generally be found curved into an arched 
form, which, however, may perhaps not be natural, but may be caused by the action of 
the water. Among these rod-like spermatozoa were several round, probably spermatic, 
cells, in most of which two bright points could be discerned, which I presume to be the 
two ends of the spermatozoon. 
I have in vain endeavoured to observe the penetration of the spermatozoon into the 
ovary. Although it is not difficult at certain seasons to find couples attached together, 
and to place them under the microscope, yet I have always found the male to be merely 
hanging on to the female by the organs provided for that purpose, and not to be at the 
* Baied, loc. cit. p. 77. 
t “ Physiologische Bemerkungen iiber die Daphnoiden,” Muller’s Arehiv, 1851. 
