30 STRUCTURE OF THE BLOOD-CORPUSCLES. 



are introduced into the circulatory system, they dilute the serum, and immediately 

 there is an endosmose of the less dense fluid into the denser contents of the cor- 

 puscles. Wheneveu water is withheld, the liquor sanguinis continually loses this 

 element by evaporation from the surface of the lungs and skin, and by the action 

 of the kidneys, becomes denser than the contents of tbe corpuscles, and exosmose 

 takes place into the surrounding medium. The cell-wall modifies the phj'sical and 

 chemical properties of every molecule of liquor sanguinis that passes through its 

 structure. 



The researches of C. Schmidt have shown that the fluid contents of the blood- 

 corpuscles contain, in addition to peculiar organic matters, a preponderance of the 

 phosphates and potash salts; whilst the liquor sanguinis contains the chloride of 

 sodium in large amount, with a little chloride of potassium and phosphate of soda. 



In the blood-cells, the fatty acids and globulin are combined both with potash 

 and soda ; whilst in the plasma, the organic materials are combined only with soda. 

 The researches of Liebig, confirmed by those of Schmidt, have shown that the 

 fluid contained in the tubules of muscles is, like that of the blood-corpuscles, ex- 

 ceedingly rich in the phosphates and potash salts. The phosphates also exist in 

 large amount in the brain. 



These facts render it highly probable that the office of the blood-corpuscles, taken 

 collectively, is that of an immense gland, which separates and elaborates from the 

 liquor sanguinis those organic and inorganic compounds which constitute the most 

 important part of the structure of the muscles and brain. 



In the Mammalia, we have an increase not only by weight, but also an immense 

 increase in numbers of the blood-corpuscles, owing to their greatly diminished size, 

 and the amount of secreting surface exposed to the intercellular fluid is correspond- 

 ingly increased. This being the case, the blood of these animals must be more 

 highly elaborated, and all their organs and apparatus correspondingly developed. 



In the present state of our knowledge, notwithstanding the numerous theories 

 which have been ably advocated by different physiologists and anatomists, we are 

 still ignorant of the exact mode of origin of the blood-corpuscles. 



Structure of the Blood-corpuscles. 



There is a great want of accordance in the descriptions of the structure of the 

 colored blood-corpuscle, and its action under different chemical reagents. Some of 

 the highest authorities are opposed to each other in their statements. I shall con- 

 fine myself merely to the results of my own observations. 



The size and form of the blood-corpuscle vary with the animal. In most of the 

 Mammalia, they are biconcave circular discs. 



In Birds, Reptiles, and Fishes, they are biconvex, ellipsoidal, or rounded discs. 

 In the Shovel-nosed Shark (Zygoma malleus) and the Loggerhead Turtle (Chelonia 

 caretla), they are very nearly of a circular form. 



In all adult Mammals — as Dogs, Cats, Raccoons, Squirrels, Deer, Sheep, Moles, 

 &c. — which I have examined, a nucleus is absent. 



In Birds, Reptiles, and Fishes, a nucleus is always present. The convexity of 

 the blood-corpuscle in these animals is due to the internal nucleus. When viewed 



