188 GLANDS IN HEALTH AND DISEASE 



sis, for even injecting directly into the blood 

 the path along which the hormones travel does not 

 materially improve matters. Or perhaps extracts 

 other than the thyroid contain substances in addi- 

 tion to the liormones that are in themselves inju- 

 rious to the system. Unfortunately for this theory, 

 we know that adrenaline, 100 per cent, pure, repre- 

 senting the adrenal hormone, does not cure Addi- 

 son's disease, a disease of the adrenals. Of course 

 it may be said with much force that adrenaline is 

 the hormone of but one portion of the adrenals, the 

 medulla, and that the hormone of the cortex of the 

 gland has not yet been isolated ; so that until this 



other of the constituents of the ductless glands. We know that 

 it does not vary in its amount in the tissues except in a minor 

 degree, that it is constantly supplied and that any single portion 

 of it functions for as long as seven weeks after administration 

 or after the gland manufactures it ; that is, it acts as a catalyst, 

 and it does not come under your definition of a hormone. It 

 acts in a manner to increase the rate of oxidation within the 

 tissues, and we can now picture the chemical changes occurring 

 which permit thyroxin to function as a catalytic agent. None of 

 the active constituents of the other ductless glands acts in this 

 way in respect to time. Adrenaline does undoubtedly act as a 

 catalyst, increasing the rate of oxidation within the cells, but it 

 functions for a very short period of time. That, to my mind, 

 is the explanation of why the adrenal and the hypophysis are so 

 closely related to the nervous system. They are strictly emer- 

 gency glands and their output must be increased and decreased 

 on demand. They function for a brief interval and that is why 

 it is impossible to administer them successfully, because only 

 relatively massive doses are given, interspersed with periods of 

 zero administration. Thyroxin is just the reverse of this. It 

 does not function immediately and lasts for as long as five to 

 seven weeks, so that it is not only unique among the glands for 

 therapeutic purposes, but it is unique in its chemical proper- 

 ties." (E. C. Kendall.) 



