THE ADRENAL BODIES 177 



substances, such as digitalin and nicotine. According to 

 Elliott, " mechanical strain is doubtless the cause of the athero- 

 matous lesions which develop after repeated intravenous injec- 

 tions. These occur in the coronary arteries which are not 

 contracted by adrenin, and must, therefore, be widely distended 

 in the general rise of blood-pressure " (see p. 175). But 

 Batty Shaw is of a different opinion. He states that if adrenin 

 is injected with an amount of amyl nitrite which is just capable 

 of neutralizing its pressor effects, arterial disease identical with 

 that produced by adrenin alone is manifested in other words, 

 adrenin produces its effects not because of its pressor ten- 

 dency, but from some other much more subtle influence. 

 " We have no experimental grounds for believing that persist- 

 ence of any stimulus should at length lead to degeneration 

 instead of hypertrophy of the middle coat." 



Braun described the degenerative changes in the arteries 

 in considerable detail, but Kaiserling does not attach much 

 importance to the effects so far as the rabbit's aorta is con- 

 cerned, because, he says, such changes sometimes occur in 

 rabbits not treated with adrenin. Etienne and Parisot have 

 come to the conclusion that elevation of the blood-pressure is 

 not in itself sufficient to induce atheroma. This effect is of a 

 toxic nature. 



Klotz has recently made the important observation that, by 

 periodic suspension of rabbits for a few minutes daily by the 

 hind-legs most advanced aortic lesions can be induced, while 

 Biedl and Braun record typical degenerative changes in the 

 aorta and its branches, as a result of repeated compressions 

 of short duration. The experiments which have been per- 

 formed up to the present time do not enable us to decide what 

 is the precise actual cause of the arterial changes after repeated 

 injections of adrenin. There seems no reason why both the 

 principal causes alleged viz., a toxic action and a mechanical 

 strain should not both have a share in the production of the 

 result. 



2. The Effects on other Structures, and the Mode and Seat 

 of Action of Adrenin. Oliver and Schafer investigated the 

 effects of adrenal extracts on the respiration of the rabbit and 

 the dog. Similar results were obtained in both, but the effect 

 is most marked in the rabbit. It occurs soon after the adminis- 

 tration of the drug, and may result in arrest of respiratory 



12 



