14 
Mr. Carlisle’s Lecture 
with numerous limbs, and variety of organs, and appendages 
of convenience, are not effected by simple apparatus ; thus, the 
skeleton which gives a determinate figure to the species, sup- 
ports its soft parts, and admits of a geometrical motion, is 
placed interiorly, where the bulk of the animal admits of the 
bones being sufficiently strong, and yet light enough for the 
moving powers ; but the skeleton is placed externally, where 
the body is reduced below a certain magnitude, or where the 
movements of the animal are not to be of the floating kind : in 
which last case the bulk is not an absolute cause. The examples 
of testaceous vermes, and coleopterous, as well as most other 
insects, are universally known. 
The opinion of the muscularity of the crystalline lens of the 
eye, so ingeniously urged by a learned member of this Society, 
is probably well founded ; as the arrangement of radiating 
lines of the matter of muscle, from the centre to the circum- 
ference of the lens , and these compacted into angular masses, 
would produce specific alterations in its figure. 
This rapid sketch of the history of muscular structure has- 
been obtruded before the Royal Society to introduce the prin- 
cipal experiments, and reasonings which are to follow : they 
are not ordered with so much exactness as becomes a more 
deliberate essay, but the intention already stated, and the limits 
of a lecture are offered as the apology. 
Temperature has an essential influence over the actions of 
muscles, but it is not necessary that the same temperature 
should subsist in all muscles during their actions ; neither is it 
essential that all the muscular parts of the same animal should 
be of uniform temperatures for the due performance of the 
motive functions. 
