324 



THE SKIN 



various sorts of natural springs. The benefits from such bathing is 

 now known to be much more indirect: hygienic and mental rather than 

 chemical. 



FIG. 178 



Nucleus 



Pigment-cell from a young salamander's skin. ieo /i- (Szymonowicz and MacCallum.) 



FIG. 179 



Pigment cells from the skin of the frog: 7, extended; II, and ///, degrees of contraction; 

 IV, wholly contracted. (Verworn.) 



Coloration. This dermal function is served by pigment-cells of various 

 colors and in many various locations on the body's surface. We need 

 not discuss the chemistry of the different pigments found in protoplasm, 

 for the coloring-matters are complex, and besides their relation to the 

 tissue-metabolism is not yet well understood. 



