172 PHYSIOLOGY. 



Because of their extremely small size, the corpuscles are not 

 really red when viewed singly with the microscope, but rather of 

 a pale yellow or even greenish tinge. It is only when millions of 

 them are en masse that the characteristic red color becomes appar- 

 ent : scarlet red in arterial blood, purplish red in venous blood. 



A peculiar inherent property of red corpuscles is to arrange 

 themselves, when withdrawn from their retaining vessels, in the 



Fig. 47. Blood-corpuscles of Different Animals. (THANHOFFER.) 



1, Proteus. 2, Rana esculenta: a, upper view of same; 6, white blood- 

 corpuscles; c, side-view of red corpuscles. 3, Triton. 4, Snake. 5, Camel. 

 6, Turtle. 7, Salamander. 8, Carp. 9, Cobitis fossilis. 10, Cuckoo. 11, Chicken. 

 12, Canary bird. 13, Lion. 14, Elephant. 15, Man: a, upper view of same; 

 &, crenated form; c, white blood-corpuscles. 16, Horse's cells in rouleaux. 

 17, Hippopotamus. 



form of rolls of coin, adhering to one another by some peculiar 

 affinity. To describe this condition the term rouleaux has been 

 used. This peculiarity becomes particularly marked when there is 

 an inflammatory state of the system. Formation of rouleaux can be 

 prevented by the injection of physiological saline-solution. 



Parasites of Blood-corpuscles. In the red corpuscles of some 

 birds and fishes the microscopist frequently notices small, trans- 

 parent spots. These are "pseudovacuoles," in which small parasites 

 may be developed and later shed into the blood-stream. Within the 



