418 ANATOMICAL AND PATHOLOGICAL OBSERVATIONS. 



The discovery of the secreting agency of the primitive cell 

 does not remove the principal mystery in which this function 

 has alsvays been involved. One cell secretes bile, another 

 luilk ; yet the one cell does not differ more in structure from 

 the other than the lining membrane of the duct of one gland 

 from the lining membrane of the duct of another. The 

 general fact, however, that the primitive cell is the ultimate 

 secreting structure, is of great value in physiological science, 

 inasmuch as it connects secretion with growth, as phenomena 

 regulated by the same laws. The force, of whatever kind it 

 may be, which enables one primary formative cell to produce 

 nerve and another muscle, by an arrangement within itself of 

 the common materials of nutrition, is identical with that force 

 which enables one primary secreting cell to distend itself 

 with bile, and another with milk. 



Instead of growth being a species of imbibing force, and 

 secretion on the contrary a repulsive — the one centripetal, 

 the other centrifugal — they are both centripetal. Even in 

 their later stages the two processes, growth and secretion, do 

 not differ. The primary formative cell, after becoming- 

 distended with its peculiar nutritive matter, in some instances 

 changes its form according to certain laws, and then, after a 

 longer or shorter period, dissolves and disappears in the inter- 

 cellular space in which it is situated, its materials passing 

 into the circulating system if it be an internal, and being 

 merely thrown off if it be an external cell. The primary 

 secreting cell, again, after distension with its secretion, does 

 not change its form so much as certain of the formative cells, 

 Ijut tlie subsequent stages are identical with those of the latter. 

 It bursts or dissolves, and throws out its contents either into 

 ducts or gland-cavities, both of which, as I shall afterwards 

 show, are intercellular spaces, or from the free surface of the 

 body. 



The general fact of every secretion bemg formed witliin 



