SOME PECULIARITIES IN REPRODUCTION. 349 
Some peculiarities in reproduction.—Many Insects, such as 
aphides, silk-moth, and queen-bee, are exceedingly prolific. The 
queen termite lays thousands of eggs, ‘‘at the rate of about sixty per 
minute” ! 
The store of spermatozoa received by the female, and kept within 
the receptaculum seminis, often lasts for a long time,—for two or three 
years in some queen-bees, 
Parthenogenesis, or the development of ova which are unfertilised, 
occurs normally, for a variable number of generations, in two Lepidop- 
tera and one beetle, in some coccus insects and aphides, and in certain 
saw-flies and gall-wasps. It occurs casually in the silk-moth and several 
other Lepidoptera, seasonally in aphides, in larval life in some flies 
(Afiastor, Chironomus), and partially or ‘‘ voluntarily ” when the queen- 
bee lays eggs which become drones. 
A few insects hatch their young within the body, or are “‘ viviparous.” 
This is the case with parthenogenetic summer aphides, a few flies, the 
little bee parasites Strepsiptera, a few beetles and cockroaches, 
Development of the ovum.—The tubes which compose 
the ovaries and lead into the oviducts begin as thin fila- 
ments, the ends of which are usually connected on each 
side. These thin filaments consist of indifferent germinal 
cells, all of them potential ova, and of mesodermic epithelial 
cells, which form the ovarian tubes, etc., and are connected 
anteriorly to the pericardial wall. 
But in most cases only a minority of these cells be- 
come ova, the others become nutritive cells which are 
absorbed by the ova, and follicle cells which line the 
walls of the ovarian tubes and help to furnish the egg- 
shells. 
There may be, indeed, ovarian tubes without nutritive 
cells (e.g. in Orthoptera), and then each tube is simply a 
bead-like row of ova, which become larger and larger 
as they recede from the thin terminal filaments and ap- 
proach the oviducts. In other cases the bead-like row 
consists of ova alternating with clumps of nutritive cells 
(e.g. in Hymenoptera and Lepidoptera). In other cases 
the nutritive cells mostly remain in the terminal region, 
but their products pass down to the receding ova. 
As there are numerous ovarian tubes in each ovary, 
and as the same process of oogenesis is going on in each, 
numerous eggs are ready for liberation at the same time, 
and are simultaneously discharged into the oviduct of each 
side. 
The eggs are large and contain much yolk. In relatively 
