THE THYMUS GLAND AND THE ADRENALS. 179 



cells contained in the gland or it may be in some cases an 

 inherent quality of all the cellular elements of a given gland. 

 In the pancreas the formation of the active agent is apparently 

 limited to an interstitial, epithelium-like tissue occurring in 

 isolated patches throughout the gland and especially charac- 

 terized by its vascularity. This epithelioid tissue is certainly 

 distinct from the secreting alveoli, and is suspected, at least, 

 of being the source of the internal secretion. Again, in the 

 suprarenals, as Schafer and Oliver have shown, the active 

 principle, which has such a marked influence upon the heart 

 and arteries, is contained only in the medulla of the gland, 

 and not in the cortex, the medulla forming about one-fourth 

 of the gland by weight." . . . "If we take the content of 

 phosphorus as a measure of the proportion of nucleic acid 

 contained in the various forms of nucleoproteids thus far 

 studied, we find exceedingly great variations in the amount 

 of this acid present in the molecule: a fact which may be taken 

 as evidence of the large number of molecular combinations 

 present in the protoplasm of different cells. Thus, from the 

 kidneys we obtain a nucleoproteid with only 0.37 per cent, of 

 phosphorus, while, as representing the other extreme, 61 we have 

 in the pancreas a nucleoproteid containing 4.71 per cent, of 

 phosphorus and in the lymphoid cells of the thymus a correspond- 

 ing body with 3.5 per cent, of phosphorus. . . . The very 

 nature of the many bases which come from the cleavage of 

 the nucleic acids outside the body; the ready convertibility 

 of these bases into other allied bodies ly oxidation and reduc- 

 tion; their own physiological action, which, though mild, is 

 marked; the possibility nay, the probability that many 

 other catabolic products may be obtained from these nucleic 

 acids; and, further, that still other nucleic acids at present 

 undiscovered may exist in the cell-protoplasm, all offer good 

 reasons for believing that the nucleins and nucleoproteids, 

 which are the most prominent constituents of the protoplasm 

 of all cells, are the most probable antecedents of the internal 

 secretions." 



81 All the italics are our own. 



12 



