92 INTERNAL ANATOMY OF INSECTS. 
in the Syrphi, but in many of their affinities, and thinks 
that it is also widely diffused amongst the Musczde*. 
I must now say something upon what I conceive to be 
the real blood of insects; for I think no one will object 
to that name being given to their nutritive fluid, though 
it does not circulate by means of a vascular system. ‘The 
chyle that is produced in the intestines of animals from 
the food, is that fluid substance from which their blood 
is formed: in insects it is not absorbed 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 toblood in its use and office? ; 
only that in these animals, as Cuvier has observed, the 
blood, for want of a circulating system, not being able 
to seek the air, the air goes to seek the blood®. The 
dispersion of this fluid appears to be universal, so that 
all the parts and organs contain it in a greater or less 
_ degree?’. In many insects, if you break only an antenna 
or a leg, a drop of fluid flows out at the wound. In larve, 
the fluid which bathes all the internal parts and organs 
is not only sufficient for their nutriment, but a large 
a Reaumur iv. 260—. > Herold Schmetterl. 24. 
© Anat. Comp. iv. 165. ¢ Marcel de Serres (p. 67). 
speaks of this fluid as being, after it has transuded through the in- 
testinal canal, a fluid in repose, which seems to indicate that it is per- 
fectly 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 evi- 
dent that it cannot be considered asa stagnant fluid, since there must 
be a constant though probably slow motion towards the points of 
absorption or imbibition. 
