APODIDjE. 
27 
numbers only. Their method of copulation, therefore, is 
as yet only conjectural. * That one copulation, however, 
is sufficient for several generations, as in the case of the 
Daphnise, &c., to be hereafter described, has been ascer- 
tained. 
Schoeffer tells us that he has carefully isolated the 
young as soon as born, and found them to produce eggs, 
from which a second generation was hatched. He also 
found that the sun and open air were necessary for this 
purpose, as he has kept them for a length of time in a 
warm chamber during winter, without their ever hatching 
their young ; but as soon as warm weather came on, and 
the vessel which they were in was exposed to the sun and 
open air, they hatched them in abundance. When taken 
and placed in a vessel of clear water they may be seen 
letting their eggs drop from the external ovary to the 
bottom of the vessel, and in warm weather the young are 
hatched from the egg in the space of about two or three 
weeks, f At first they are very different from the parent, 
undergoing a series of changes before they become fully 
developed. The egg has two membranes ; one external, 
coriaceous, the other internal, tender, and pellucid. When 
it is ripe the external membrane opens at the upper part, 
showing there a small red body, which may speedily be 
observed to be in motion. This motion increases, at- 
tempts seem to be made to burst the internal membrane ; 
and then, after perhaps half a day, it suddenly leaps out 
from its envelope, a living animal. The egg then falls to 
the bottom, and loses its red colour, while the young 
animal commences forthwith its motion to and fro through 
the water. At first it is of a rosy colour, and an oblong 
* Zaddach imagines that he had discovered the male organ. “ It consists,” 
he says, “of a small round body near the mesial line on the dorsal part of 
the last ring of the body, with a small portion on its apex surrounded by an 
elevated margin.” He had traced a nerve running to it. Should Kollar’s 
discovery be confirmed, this statement must “be attributed,” to use Bur- 
meister’s words, “ to a defective microscopic examination of the organs of 
generation.” 
+ Zaddach says twenty days. 
