192 STATES OF INSECTS. (Larva.) 
between the new skin and the old *. Whether the spznes, 
simple or compound, lately described to you, that arm 
some larve are similarly circumstanced, seems not as yet 
to have been ascertained; but as the spinous ones of 
certain saw-flies and Lepidoptera at their last moult have 
no spines, the presumption is, that, whether incased or 
not, they are mere appendages of the skin on which they 
appear. A new set of hairs, therefore, and probably of 
spines in spinous larvee, accompanying each skin, and 
these varying very much in size, composition, &c. though 
a new membrane may be admitted to be formed from an 
action in the rete mucosum without a pre-existent germe 
of it, it seems not easy to conceive how these hairs and 
spines can spring up and grow there, each according to 
a certain law, without existing previously as a kind of 
corculum or punctum saliens ; and that the germes of the 
tubercles, in which the hairs are so generally planted, 
according to a certain arrangement and in a given num- 
ber, should also pre-exist, seems most consonant to 
reason. ‘These and the several skins may all co-exist in 
their primordial germes, and remain beyond the discovery 
of our highest powers of assisted vision, till a certain 
period when they may first enter the range of the mi- 
croscope-aided eye. It does not therefore follow, be- 
cause these primordia semina rerum are not discoverable, 
that therefore they may not exist. Our faculties and 
organs are too limited and of too little power to enable 
us to see the essences of being. 
Upon the supposition that the hypothesis of Swam- 
merdam is the true one, we may imagine that the enve- 
lope that lies within all the rest is that which covers the 
° N, Dict. d Hist. Nat. vi. 290. 
