The Relative Size of Red Blood Corpusele and Brain. 29 



mixed arterial blood being sent to the left lung, while the right 

 lung is usually aborted; the lung is of loose texture and small rapac- 

 ity, the incomplete circulation is due to the pecular communication 

 of the heart with the great vessels, hence a low temperature and 

 sluggish motion. 



The product of waste and repair in reptiles during their period 

 of torpidity, can bear no relation to that of warm blooded animals; 

 this limited waste is evidently due to a very much retarded flow of 

 imperfectly oxygenated blood. 



I have considered the temperature in this class for the purpose 

 of showing that the animal having the highest degree of tempera- 

 ture also has the smallest red corpuscle, the largest brain, and the 

 greatest degree of activity. The brain to body, in size, is 1:321, 

 and [jresents on its upper surface a great resemblance to that of 

 fish, while their hemispheres are smooth, non convoluted, hollow 

 internally, and surpass in circumference, the second portion of the 

 brain; compared with the higher order of animal life, their brain 

 is less developed than the spinal cord, while their cerebellum is 

 more highly developed than that of fish. The nerve tube or fibre 

 of this class measures fa'go of an inch in diameter or about gs'oo of 

 an inch less than that of the fish. The lizard has the smallest red 

 corpuscle, measuring tiS 5 of an inch in diam. and a brain propor- 

 tionately large, something near ^'j the weight of the body. 



It is the most active of this class, while the siren and the [)roteus 

 are the most sluggish, each having a corpuscle measuring 4^0-of an 

 inch in diam; The measurments of a few of this class is found in 

 the following table. 



Size of Corpuscle. 



Lizard 



Alligator , 



Tortoise 



Common Frog 



Toad ,o',5 



Triton ^\^ 



Siren -^\^ 



Proteus 4 J 5 



We have now to consider our third subdivision, that of birds. 

 Birds are the most active of living creatures: they have a nervous 

 system that is relatively smaller than that of mammals and the ratio 

 of the size of the red corpuscle to the brain — which is i:2r2 — 

 is about the same. 'I'heir jnilse is more rapid, averaging 150 |)er 



I £ 3 5 

 - J_ 



13 2 4 



.1 _ 



i 25 2 



i r 8 



