398 THE DUCTLESS GLANDS 



According to modern views, the chromaphil tissues form a 

 series which may be regarded as sympathetic glandular organs 

 and which are widely distributed along the course of the 

 vegetative fibres. 



The majority of writers still deal with the adrenal bodies as 

 if they represented functional entities. But as far as is defi- 

 nitely known, the chromaphil tissues physiologically have 

 nothing whatever to do with the adrenal system (or adrenal 

 cortex and " accessory cortical bodies "). 



The pancreas, along with its islets of Langerhans, is an out- 

 growth from the alimentary canal, and so might be regarded 

 as belonging to the same system as the branchial cleft organs. 



We have not sufficient information to guide us to a decision 

 as to whether we ought to regard morphological and embryo - 

 logical connections as an indication of a probable physio- 

 logical relation. 



Elliott quotes Gaskell as classifying together, on morpho- 

 logical grounds, the pituitary body, the thyroid and the adrenal 

 cortex, being all modified from the coxal glands, that is, the 

 segmental excretory apparatus of some primitive arthropod 

 type. But Gaskell's theory, so far as the ductless glands are 

 concerned, is open to grave criticism, and the theory as a whole 

 is, I believe, not generally accepted by morphologists. 



It must be remembered that a normal gland may either 

 excite or moderate the activity of another. If an exciting 

 organ be suppressed, there will be insufficiency of the second, 

 and so we get a diminution of two functions. If a moderating 

 organ be reduced in activity, the disturbance occurring in the 

 second gland will be overaction. And further, one gland may 

 exercise an exciting influence upon a second and a suppressing 

 action on a third. In these actions both the sympathetic and 

 the autonomic systems may take part. 



The evidences in regard to endocrinous interrelationships are 

 derived from pathological anatomy, from clinical observation, 

 and from experimental investigations. 



A. Interrelationships involving the Thyroid Gland 



Action of the Thyroid upon the Adrenal Bodies 



Sub-thyroidism has not been shown to have any effect upon 

 the adrenal bodies, although attempts have been made to show 



