Experimental Arteriosclerosis. 



49 



Two which were given digalen intravenously were negative 

 after 52 and 64 injections. 



Four were given acetate oflead intravenously. In two of these, 

 by using a very dilute solution, 1-2,000, dose 30 minims, we 

 managed to give 26 injections. Negative. Two others received 

 subcutaneous injections which produced abscesses. 



In the whole series of over 80 rabbits there are but 12 positive 

 results. 



Fourteen rabbits weighing considerably over 2,000 grams each, 

 not subjected to any experimentation, were examined for aortic 

 lesions with negative results. 



A close scrutiny of the reports of other observers shows that 

 they also have had many negative results. Adrenalin seems to 

 give the best and most uniform results, though Kayserling in eight 

 rabbits treated with adrenalin saw no macroscopic lesions and only 

 a few microscopic changes. On the other hand, positive results 

 have been obtained from substances differing most widely in chem- 

 ical composition and physiological action, even from normal saline 

 solution given in large quantities. On the whole it may be said 

 that blood-pressure-raising drugs give the best results. 



The extent and gravity of the lesions do not seem to be alto- 

 gether dependent upon the number of injections given — Erb saw 

 complete calcification of the aorta after a single injection of adren- 

 alin, while we and many other observers have found very little or 

 nothing after a great many injections. All attempts thus far to 

 produce similar lesions in other animals, such as dogs and monkeys, 

 have failed. The lesions seem to occur in rabbits, though prob- 

 ably but rarely, spontaneously and especially in such animals 

 debilitated by old age and disease. 



Much further investigation is necessary, but the following con- 

 clusions seem to us warranted in the present state of our knowledge : 



It is still very uncertain what relation the experimental results 

 produced in the aorta of rabbits by the intravenous injection of 

 adrenalin, nicotin and other substances, may bear to human athe- 

 roma or arteriosclerosis. In the present state of our knowledge 

 we are not justified in identifying the two processes. It seems 

 probable that rabbits have a special predisposition towards these 

 lesions. Young and healthy animals seem able to resist and render 



