32 Cuicinnati Society of Natural History. 



The elephant, in which we find great physical and mental en- 

 tlurance, is capable of accomplishing a greater amount with greater 

 energy exerted in a given time than any other, but like the ostrich 

 has comparatively little activity; he has the smallest brain com 

 pared to the size of the body, weighing ten pounds or ji^ of weight 

 of the body, the red corpuscle measures 27*4 6 of an inch in diame- 

 ter. Both respiration and circulation are very slow, the former 

 being 8 and the latter 36 per minute; this is an another illustration 

 that a large corpuscle and a small brain are associated with a slow 

 pulse and respiration and a low drgree of temperature and activity. 



The most active mammals have a greater amount of gray, as 

 compared to white matter in the brain, and is in proportion to the 

 number and depth of the convolutions, which although not wanting 

 in many vertebrates, are always found in the cerebellum of mam- 

 mals, the greater portion of which is composed of gray matter. 



It has been found that the gray matter is more vascular than 

 the white, tlierefore the amount of blood that would ])ass through 

 a, given quantity of each in a given time, would be much greater in 

 the the gray than in the white; this facilitates a greater rate of 

 molecular change, and the change is influenced by the rate of res- 

 piration and circulation. 



Of mammals, the Java Musk deer has the smallest known red 

 corpuscle; it measures rosoa of an inch in diameter ; there seems 

 to be no available record concerning the weight of its brain, how- 

 ever the animal is known to l)e of the most active of its class. In- 

 vestigations concerning this class of vertebrates seems to have 

 been more thorough and more general than of any other class, as 

 may be shown by the following table, which includes (juite a variety. 



Ratio of tlw l>rai)i to the body. 



Ox I : 860 Sheep i : 192 



Wild Boar i : 670 Hedge Hog. .... i : 168 



Domestic Boar . . i : 412 Ass ... i ; 154 



Horse i : 400 Rabbit i : 152 



Stag I : 290 Bat. I : 96 



Wolf I : 230 Baboon r : 86 



Hare 1:228 Rat i: 76 



Calf I .• 2 1 9 Demur i : 61 



Fox I : 205 Gibbon 1 : 48 



Buck I : 1 94 Mouse i ; 43 



Ape ... I : 24 



