22 NOTES ON 
immerses the lower extremity of her body, and 
deposits, at intervals, a single egg. These eggs, 
when examined by a microscope, appear of an 
oblong form, having the fore part terminated | 
in a point of a blackish colour.* The young, 
when they first emerge from the ova, are very 
small; indeed, are almost imperceptible. In a 
few days they grow to the length of the tenth 
of an inch, and cast their exuvie the first time. 
I have taken them of this size, in the months 
of June and July, sporting in ponds containing 
healthy aquatic plants. If these creatures be 
examined at this period, their heads will be 
found much larger, in proportion to the body, 
than at a more advanced stage of their growth. 
Indeed, by unassisted vision, they now appear 
like dark specks, having a tail attached to them. 
They grow rapidly if well supplied with food, 
and, when about two-tenths of an inch long, 
begin to exhibit all the courage and ferocity of 
the mature larva, attacking with extended jaws 
beings ten times their own size, and, when in- 
commoded, even destroying those of their own 
species. 
The ramifications of the two large vessels 
(trachee), running along the back, are now 
* Swammerdam’s Book of Nature, p. 98. 
