10 GLANDS IN HEALTH AND DISEASE 



Then again, McCarrison, an English investiga- 

 tor stationed in India, has shown that the adrenal 

 glands of birds suffering from polyneuritis are 

 much enlarged, and that the adrenaline content of 

 these glands is increased. As we shall see, the 

 adrenals, like the thyroid, are glands of internal 

 secretion, and adrenaline is the active hormone 

 present in these glands. Even more remarkable 

 is his discovery that though the adrenals become 

 enlarged, the other ductless glands degenerate and 

 tend to disappear altogether. It would seem as if 

 there were some connecting link between vitamine 

 B (the vitamine the absence of which causes poly- 

 neuritis) and adrenaline; as if a diet containing 

 adequate amounts of vitamine B had a restraining 

 influence upon the output of the adrenal hormone. 



But we must not stretch these points too far, 

 at least, not until these experiments have been re- 

 peated and extended. In the meantime it is well to 

 point out some obvious differences, if only to 

 strengthen our judicial attitude. 



Vitamines are very susceptible to heat; or more 

 accurately, to a combination of heat and oxidation 

 (exposure to air) ; hormones do not seem to be 

 destroyed at a temperature even of boiling water; 

 at least, the last statement is true of secretin (the 

 intestinal hormone) and one or two others that 

 have been studied. Then again, in two instances 

 adrenaline (from the adrenal gland) and thyroxin 



