560 Dr. BailLie’s Account of a 
in all human inventions, and therefore there is no reafon why 
nature fhould not fometimes deviate from her ordinary plans. 
Accordingly we find there is much variety in animal ffructure ; 
but this does not commonly affedt the animal functions. 
Under this reffridtion the variety is lb great in the appearances 
of every part of an animal, that it is almoff impofiible to exa- 
mine any two animals of the fame lpecies without remarking 
many differences. 
In the bony compages of an animal we find little variety in 
the extremities of bones where there is the apparatus of a joint, 
hecaufe a particular fhape is beft adapted to a particular kind or 
latitude of motion. In other parts of the bones, where a 
difference of features is not material, there is great variety, as 
in the foramina, deprefilons, ridges, and futures of bones. 
The fame general rule will apply to variety in mufcles. The 
principal object is a certain infertion near a joint, fo as to give 
a determined direction of motion. With refpedt to fuch in- 
lertions, there is, comparatively fpeaking, little variety ; but 
there is a great difference in the bodies and connections of muf- 
cles, which have no fhare in the regulation of the motion. 
There is no part of an animal where there is a greater lati- 
tude of variety than in the diffribution of blood veffels. The 
reafon of it is very obvious. The only objedt in the diffribu- 
tion of blood veffels is, to carry blood to every part of the 
body and bring it back to the heart. The parts of an animal, 
in order to be fupported, muff be vifited by fucceflive changes 
*f frefh blood ; but it furely cannot be an objedt of impor- 
tance whether the blood paffes by one rout or another. Hence 
the variety in blood veffels is extremely great. Still, however, 
rthere is a method in the deviations of nature, fo that they 
may 
