MAMMALS. 



9 



are very small, -y^ of an inch ; while in the sloth they are y^-, and in the ape, which 

 is comparatively inactive, -j^Vo- But, on the other hand, in the dog, which is quite 

 active, we have a corpuscle of ^Yo of an inch, and in the ox, which is certainly not so 

 active, the diameter of the corpuscle is T ^V<5- f an inch. Although this relation hetween 

 the size of the blood-corpuscles and muscular activity is not invariable, it is certain that, 

 the higher we go in the great classes of animals, the smaller are the blood- corpuscles ; 

 the largest being found in the lowest orders of reptiles, and the smallest, in the mam- 

 malia. The blood of the invertebrates, with a few exceptions, contains no colored cor- 

 puscles. 



Table of Measurements of Red Corpuscles. 



This table is taken from the table of Mr. Gulliver, published in the Sydenham edition of Hewson's 

 Works, page 237. Nearly five hundred measurements were made by Mr. Gulliver ; and of these, 

 one hundred of the most important have been selected. It will be observed that the diameter of 

 the human blood-corpuscle is greater than that generally given. It must be borne in mind that all 

 these measurements are mere approximations ; but they are useful, as showing the relations of the 

 corpuscles in different animals, and enabling us to distinguish the blood of the human subject from 

 that of some of the inferior animals. The measurements are all given in fractions of an English 

 inch ; and, in making the selections, the common names of the animals have been substituted for 

 the technical names given in the original. 



Mammals. 



