164 INTERNAL ANATOMY OF INSECTS. 
larva and sometimes even ofa pupa. Of the first descrip- 
tion are certain Diptera, the Aphides, and the Scorpion. 
Reaumur has described two modes in which the lar- 
ve of the first are arranged in the matrix of the mother. 
In some they are heaped together without much ap- 
pearance of order, being placed merely parallel to each 
other; but in others they are arranged in a kind of ri- 
band—the length of the little animals, which are also 
parallel, forming its thickness—rolled up like the main- 
spring of a watch’. These larve in general are not di- 
vided into two masses corresponding with the pair of 
ovaries in other insects, but form only a single one‘. 
You must not suppose that these littie fetuses lie naked 
in the womb of the mother; each has its own envelope 
formed of the finest membrane, which, however, is not 
entirely divided from that of those adjoining to it, but 
appears to be one tube, which becomes extremely slen- 
der between each individual, so as when drawn out to 
Jook like a chain’. Reaumur seems to have thought 
that in these flies the larvee were never confined in any 
other case or egg*; but De Geer sometimes found eggs 
in the body of Musca carnaria, though most generally 
larvee, from which he conjectures that it is really ovo-vi- 
viparous, the eggs being hatched in the body of the mo- 
ther’. As these flies are all carnivorous, and their of- 
fice is to remove putrescent flesh, you may see at one 
glance the object of ProvipENce in this law of nature— 
that no time may be lost, and the animal exercise its 
function as soon as it is disclosed from the matrix. 
_ The Aphides, so fruitful in singular anomalies, are oyo- 
*@ Prare XXII. Fic. 4, > Tbid. Fic. 3. 
° Reaum. iy. 414, 0 Wiidet xxvii 1 Asolo 
© bid, 404. * De Geer vi. 63—. 
