on Muscular Motion. 
207 
founded upon the anatomical structure of a complex muscle, 
must be overturned. 
The simplicity of form, in the muscular structure of this 
species of hydatid, makes it evident, that the complex organi- 
zation of other muscles, is not essential to their contraction and 
relaxation, but superadded for other purposes ; which naturally 
leads us to suppose, that this power of action, in living animal 
matter, is more simple, and more extensively diffused through 
the different parts of the body, than has been in general 
imagined. 
From these observations we shall find, that the inquiries 
hitherto made, into the principle of muscular motion, by in- 
vestigating the muscles of the more perfect animals, which 
are most remarkable in their effects, and obviously most de- 
serving of attention, have been too confined. 
From our inquiry into the structure of muscles, in different 
animals, we readily discover, that those above mentioned, al- 
though the most perfect in their organization, are at the same 
time so complicated, for the purpose of adapting them to a 
variety of secondary uses, that they become of all others, the 
kind of muscle least fitted for the investigation of the principle 
itself. 
In the present imperfect state of our knowledge respecting: 
animal life and motion, a physiologist, who would select a 
complex muscle, with the view of discovering, from an exami- 
nation of its structure, the cause of muscular contraction, would 
resemble a man, ignorant of mechanics, who should consider a 
watch as the machine best constructed to assist his inquiries 
respecting the elastic principle of a spring ; which, at first sight, 
must appear absurd. For although the spring is the power 
