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HUMAN BIOLOGY 



cell (e). If the conductile process of the latter were hkewise 

 magnified 700 times it would extend downward beyond 

 the hmits of the page, a distance of 1568 feet. 



Fig. I. Diagrams to illustrate the shape of different kinds of cells. 

 A. Red blood corpuscle. B. Leucocyte, c. Flattened cells of skin. d. Muscle 

 cell. E. Nerve cell. f. Group of pancreatic cells. (Magnified 700 times.) 



Another method is to preserve the cells, cut them into 

 very thin shces, or sections, and stain them. Such sections 

 can be made 1/25,000 inch in thickness. A section through 

 the skin is illustrated at c in Figure i. It shows how the 

 cells become flattened as the surface is approached. Diagram 

 F illustrates the grouping of secreting cells in the pancreas. 



CELLS BEHAVE LIKE INDIVIDUALS IN A LARGE COMMUNITY 



Despite their microscopic dimensions, the cells of the 

 body have a certain measure of independence like individuals 

 in a large community, a comparison originally made by 

 Virchow (1858). While they are members of this community 

 they grow, reproduce their kind, die and are destroyed by 



