306 THE BIOC08MOS PARTICULARIZED. 



the white corpuscles perform the function of 

 police and remove all disturbing substances. 

 Malarial fever is produced in the blood by a 

 parasite which comes from the bite of a cer- 

 tain kind of mosquito (anopheles). The aver- 

 age man contains about six quarts of blood. 

 Noteworthy is the fact that the organs of 

 circulation, lungs, heart, blood-vessels, have 

 the tendency to be double in correspondence 

 with the bi-lateral symmetry of the whole 

 body. On the other hand the organs of di- 

 gestion have the tendency to be single (stom- 

 ach, pancreas, spleen, liver though lobed, and 

 the intestinal canal, though of several sizes 

 and forms). Digestion is a more primitive, 

 vegetal function than circulation of the blood. 

 Also the digestive organs seem on the whole 

 less amenable to the central organ (brain) 

 than the circulatory, in which fact the Plant 

 is again suggested. The word circulation im- 

 plies the circular movement, which is in de- 

 cided contrast with the digestive movement. 

 Connected with the round of the blood is 

 the lymphatic circulation, which starts in the 

 capillaries with the watery part of the blood 

 (plasma), and floats in a perpetual bath the 

 cells of various tissues, bringing to them nour- 

 ishment as well as carrying off their waste. 

 The lymph is always accompanied by some 

 soldiers, the white corpuscles (the aforesaid 



