184 THE DUCTLESS GLANDS 



It has been stated recently that rhythmic contractions of 

 arteries occur normally in the rabbit's ear and that adrenin 

 augments these contractions. 



There seems to be considerable difference of opinion as to the 

 effect of adrenin on the secretion of sweat. 



Redfield suggests that the melanophores of the amphibia 

 are controlled by adrenin in the circulation. 



Cats appear to be peculiarly liable to collapse after intra- 

 venous injection of adrenin under light chloroform anaesthesia. 

 Full chloroform anaesthesia appears to be absolutely protective. 

 There is probably some unknown condition of the heart under 

 the influence of low percentages of chloroform, which renders 

 it incapable of accommodation to vascular strain. 



In the experience of the present writer, also, it has very 

 frequently happened that dogs have been killed by a dose 

 of adrenin (administered intravenously) which it was expected 

 would only be sufficient to produce a moderate rise of blood- 

 pressure. This has occurred with both adrenal extracts and 

 the purified adrenin, and it is not clear that it is dependent 

 on the nature or amount of the anaesthetic employed. The 

 phenomenon seems to depend upon a peculiar idiosyncrasy in 

 some animals, and is comparable to what was found in respect 

 of the general effects produced in various animals by sub- 

 cutaneous injections (see p. 159). 



A large amount of work has been carried out upon the 

 antagonism between adrenin and various other drugs. In 

 many respects there appears to be a true antagonistic action 

 between adrenin and calcium chloride, although the latter 

 substance does not hinder the production of adrenin arterio- 

 sclerosis. Adrenin is also stated to act as an antidote to 

 poisoning by strychnine, aconitine, and belladonna. A 

 pharmacological antagonism is alleged between adrenin and 

 secretin, while adrenin exercises no action which can be 

 regarded as antagonistic to that of albumoses and of pilocarpine 

 upon the pancreatic and salivary secretions. It is stated 

 that the chlorides of calcium, barium, magnesium, and potas- 

 sium can neutralize the mydriatic action of adrenin. 



The table on pp. 187-191, taken from Biedl, gives a summary 

 of the chief actions of adrenin and a comparison between these 

 actions and those produced by stimulation of nerves belonging 

 to the sympathetic and autonomic systems. 



