The Cells of the Body n 



in common with other cells. Thus the power 

 of reproduction is in them almost if not quite 

 completely absent. They can also no longer 

 seek out and take up crude food, but it has to 

 be prepared for and brought to them, and in 

 order that this may be done certain other cells 

 in the body develop the power of elaborat- 

 ing a peculiar fluid gastric juice, which helps 

 to change the crude food so that it finally 

 becomes fitted for the nourishment, among 

 others, of the special workers, the muscle 

 cells; other cells the red blood cells de- 

 velop the capacity of bringing them oxygen, 

 and in doing so have lost many capacities 

 which are possessed by lower forms. Other 

 cells develop in a peculiar way to form the 

 nerves by which all the various parts of the 

 body are brought into harmonious action, and 

 so on. Thus we see in the higher animals 

 each highly developed cell working for the 

 others as well as for itself and for the organ- 

 ism as a whole, only its chief endeavor is con- 

 centrated in some one special thing, and as a 

 result of this concentration some of the more 

 general cell powers are lost or diminished. 



