ANATOMY 



cup. Small as they are, and constituting an in- 

 considerable fragment of the body as a whole, 

 they yet exert a most profound influence, and are 

 of vital importance to the well-being of the in- 

 dividual. It is known that the ductless glands 

 manufacture substances so infinitesimal in amount 

 that their nature is but obscurely understood. 

 These substances pass from the ductless glands 

 into the blood-stream, whereby they circulate all 

 over the body. The amount that can reach any 

 individual cell of the body must be so inconceiv- 

 ably small as to be quite beyond computation. 



These ductless glands and the substances which 

 they manufacture or internal secretions, as they 

 are termed are being actively investigated by 

 the physiologist. At the same time they are of 

 very special interest to the anatomist, as they 

 exert a potent influence on the building operations 

 of the body. Moreover, it is known that they can 

 and do modify the building of the skeleton in a 

 truly remarkable manner. 



The evidence is chiefly negative, and is mainly 

 founded on the events occurring when the ductless 

 glands are the seat of disease, which may be of 

 more than one kind. Under some abnormal con- 

 ditions the influence of one of the ductless glands 

 may be diminished, under other circumstances 

 it may actually be increased. It is known, for 

 example, that in certain conditions of one of the 



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