86 ME. LUBBOCK’S ACCOUNT OF THE TWO 3IETHODS OF BEPEODUCTIOK 
In order to determine, if possible, the condition of the germinal vesicle at the time of 
deposition, I crushed these two eggs, and found them, as well as many others recently 
laid, to consist mainly of minute globules, chiefly -000083 to '000125 of an inch in dia- 
meter, but some as large as -000250. There were also some large cells from -0014 to 
'0001 of an inch in diameter, and apparently containing a number of the smaller. I 
could never find in any deposited ephippial egg any of the large oil-globules so charac- 
teristic of the agamic eggs, nor any of the “ mother-cells ” or germinal vesicles so common 
in the ovary, nor did they appear to possess a double egg-skin. Moreover, if, when the 
egg has been crushed between two pieces of glass, the upper piece is moved backwards 
and forwards on the lower piece, the little cells collect into rod-hke bundles, remaining, 
however, distinct, hke Plate VII. fig. 11 ; whereas, if the same power be applied to an 
agamic egg, the globules appear to run together into a rod, like Plate VII. fig. 12, 
and are, therefore, probably not true cells. 
The ephippium, which at the time of the deposition of the eggs w’as reddish or light- 
brown, becomes gradually brown and then black, the protuberances containing the eggs 
being often darker than the rest. This dark colour seems to be produced by a deposition 
of granules, which commences gradually after the exuviation of the preceding carapace, 
and occupies in summer about four days. As the ephippium becomes darker and more 
matured, so the line dividing it from the rest of the carapace becomes more strongly 
marked, and the connexion more slight, until at the time that the carapace, of which 
the ephippium forms a part, is cast, the ephippium is either actually separated, or at any 
rate can be detached with the greatest ease, and the carapace then looks as if a piece 
had been cut out from it. 
If the outer “ saddle ”- or “ pod ”- shaped ephippium is opened, another smaller, but 
similar case is found inside, enclosing the two eggs. This has been mentioned by all 
writers on the subject, but no one, so far as I know, has explained the mode of origm, 
or understood the true nature of it. 
It was also some time before I understood this question; but at length, observing one 
day a specimen mth a black ephippium, I remarked that it was already detached along 
the lines s, s (Plate VII. fig. 6) from the rest of the carapace, so that I had no difficulty in 
entirely removing it without injuring the animal; and I then found, to my great sm-prise, 
that the “ inner valve,” instead of being attached to the outer one, along the back hmge, 
as the descriptions of Steauss*, MiLNE-EnwAEDsf, and OwenJ had led me to expect, 
was actually separated from the outer valve by the new carapace, and was, in fact, in the 
receptacle between the new carapace and the back. 
This artificial removal of the outer valves of the ephippium I repeated several times, 
and always with the same result. If the operation is effected near the time at which the 
ephippium would naturally be cast, it may be efiected without in any way hiu-tmg the 
Daphnia, which swims about afterwards as if nothing had happened. After a short 
time, the inner case or valve may be observed slipping out behind from between the 
* L. c. p. 415. 1. 27. ' f L.C. p. 377. 1. 36. + L. c. p. 324. 1. 21. 
