176 INTERNAL ANATOMY OF INSECTS. 
of which we are speaking, by the name of Jibrine. By 
the abundance of azote or nitrogen that enters into its 
composition, it possesses a character of animalization 
more marked than any other animal substance ; and its 
elements are so approximated in the blood, that the 
slightest stagnation causes them to coagulate : and the 
muscles are without doubt, in the living subject, the 
only organs that can separate this matter from the mass 
of blood, and appropriate it to themselves 3 . The 
primary bundles of muscles are formed of the simple 
fibres, and the secondary are the result of an aggrega- 
tion of the primary. The smaller bundles are not al- 
ways exactly parallel to each other, but must in many 
cases diverge more or less, to produce those variations 
in shape observable in the muscles themselves : there 
are intervals therefore between the bundles, which in 
some animals are filled by a cellular substance b . Pro- 
bably much of this statement will apply in most in- 
stances to the muscles of insects, but we may conclude 
that the globules that form them are infinitely smaller . 
Lyonet has given some interesting observations with 
regard to those of the caterpillar of the Cossus : he de- 
scribes them as of a soft transparent substance, capable 
of great extension, covered and filled by silver tubes of 
the bronchia:, penetrated by the nerves, and containing 
oily particles. Each muscle was enveloped in mem- 
brane, and was composed of many parallel bands, con- 
sisting of bundles of fibres enveloped likewise in sepa- 
rate membranes. The fibres themselves, (but it is doubt- 
ful whether he arrived at the ultimate term of muscular 
fibre,) in a favourable light and under a good magnifier, 
■ Cnv. ubi snpr. 90-. b Cuv. Ibid. i. 89—. 
' See above, p. 85. 
