BLOOD. 125 



The inorganic constituents are chiefly sodium and potassium chlo- 

 rids, sulphates and phosphates together with calcium and mag- 

 nesium phosphates. The sodium chlorid is the most abundant, 

 amounting to about 5.5 parts per thousand. The alkaline salts 

 impart the alkaline reaction and promote the absorption from the 

 tissues of the carbon dioxid. 



Excrementitious matters are represented by carbonic acid, urea, 

 creatin, creatinin, urates, oxalates, etc. ; they are absorbed from the 

 tissues by the blood and conveyed to the excretory organs, lungs, 

 kidneys, etc. 



Gases. Oxygen, nitrogen, and carbonic acid exist in varying 

 proportions. 



BLOOD-CORPUSCLES. 



The corpuscular elements of the blood occur under two distinct 

 forms, which, from their color, are known as the red and white 

 corpuscles. 



The red corpuscles as they float in a thin layer of the liquor 

 sanguinis are of a pale straw-color ; it is only when aggregated in 

 masses that they assume the bright red color. In form they are 

 circular and biconcave ; they have an average diameter of ^aVo" 

 of an inch. 



In mammals, birds, reptiles, amphibia, and fish the corpuscles vary 

 in size and number, gradually becoming larger and less numerous 

 as the scale of animal life is descended, e. g. : 



TABLE SHOWING COMPARATIVE DIAMETER OF RED CORPUSCLES. 



Mammals. Birds. Reptiles. Amphibia. Fish 



Man, g^ Eagle, lg \ 5 Turtle, T ^ T Frog, T1 fo Perch, 51 fe ff 



Chimpanzee, -^^ Owl, y^g Tortoise, j^j Toad, JT fa^ Carp, ^yW 



Orang, ^ y Sparrow, BI ^ ff Lizard, ' Proteus, ^v pike W<yo 



D og", s*w Swallow, y fa Viper, ^y.5 Siren, ^ Eel, T7 1 J5 



Cat, ? V? Pigeon, >,, Amphiuma, g 3 



H g, JsVo Turkey, ^\-s 



Horse, ZSQV Goose, j^gg 



Ox > iisW Swan, j^s 



In man and the mammals the red corpuscles present neither a 

 nucleus nor a cell wall, and are universally of a small size. They can 

 be .readily distinguished from the corpuscles of birds, reptiles, and 

 fish, in which animals they are larger, oval in shape, and possess a 

 well-defined nucleus. 



