98 INTERNAL ANATOMY OF INSECTS. 
in the larva, though it does not circulate by means of a 
vascular system. The chyle that is produced in the in- 
testines of animals from the food, is that fluid substance 
from which their blood is formed : in insects it is not ab- 
sorbed by the lacteals, but transpires through the pores 
of the intestinal canal into the general cavity of the body, 
where, being exposed to the influence of the oxygen in 
the air-vessels, it becomes, though retaining its colour, 
a different fluid from what it was before, and analogous 
to blood in its use and office a ; only that in these animals, 
as Cuvier has observed, at least in their perfect state, the 
blood, for want of a circulating system, not being able 
to seek the air, the air goes to seek the blood b . The 
dispersion of this fluid appears to be universal, so that 
all the parts and organs contain it in a greater or less 
degree c . In many insects, if you break only an antenna 
or a leg, a drop of fluid flows out at the wound. In larva?, 
the fluid which bathes d , or visits, all the internal parts and 
organs is not only sufficient for their nutriment, but a 
large quantity of seemingly superfluous blood remains that 
is not wanted for this purpose. This is expended in 
the production of the caul or epiploon (Corps graisseux 
a Herold Schmctterl. 24. h Anat. Comp. iv. 165. 
c Marcel de Serres (p. 67.) speaks of this fluid as being, after it 
has transuded through the intestinal canal, a fluid in repose, which 
seems to indicate that it is perfectly stagnant ; but when we consider 
that it is not only incessantly entering the body and making its way 
to every part, but is also, by means of the various secretory organs, 
constantly converted into new products, and so going out again in 
many cases, it will appear evident that it cannot be considered as a 
stagnant fluid, since there must be a constant though probably slow 
motion towards the points of absorption or imbibition. 
d Dr. Kidd (pinks. Trans. 1825. 236.) did not find the abdominal 
viscera of the mole-cricket thus circumstanced, nor more lubricated 
than the intestines of the higher animals. 
