INTERNAL ANATOMY OF INSECTS, 169 
of which we are speaking, by the name of fbrine. By the 
abundance of azote or nitrogen that enters into its com- 
position, it possesses a character of animalization more 
marked than any other animal substance; and its ele- 
ments 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?. - The primary bun- 
dles of muscles are formed of the simple fibres, and 
the secondary are the result of an aggregation of the 
primary. The smaller bundles are not always exactly 
parallel to each other, but must in many cases diverge 
more or less, to produce those variations in shape ob- 
servable in the muscles themselves: there are intervals 
therefore between the bundles, which in some animals 
are filled by a cellular substance®. Probably much of 
this statement will apply in most instances to the mus- 
cles of insects, but we may conclude that the globules 
that form them are infinitely smaller‘. Lyonnet has 
given some interesting observations with regard to those 
of the caterpillar of the Cossus: he describes them as of 
a soft transparent substance, capable of great extension, 
covered and filled by silver tubes of the bronchia, pene- 
trated by the nerves, and containing oily particles. Each 
muscle was enveloped in membrane, and was composed 
of many parallel bands, consisting of bundles of fibres 
enveloped likewise in separate membranes. The fibres 
themselves, (but it is doubtful whether he arrived at the 
ultimate term of muscular fibre,) in a favourable light 
@ Cuv. wbi supr. 90—. > Cuy. Ibid. i. 89—. 
© See above, p. $4. 
