CARDIOVASCULAR CHANGES DURING CEREBRAL ANEMIA 35 



closing the first occlusion that followed ligation of the adrenals. At 

 this time pressure fell to 30 or 40 mm. Hg. a level 20 to 30 mm. lower 

 than in the intact animals at a corresponding time. In spite of the 

 subsequent return of respiration and other bulbar activities, the pres- 

 sure remained uniformly low. A return of the corneal reflex was ob- 

 tained even at this reduced level. The level of blood pressure main- 

 tained between successive occlusions varied somewhat. On comparing 

 the amount of recovery of blood pressure in a given animal after occlu- 

 sion, and the number of occlusions obtainable, it was found that, at 

 least in the extreme cases, a direct variation could be noted. The two 

 very vigorous animals which gave eight reactions after ligation of the 

 glands, cats 52 and 54, showed a recovery of pressure of 40 to 50 mm. 

 during the period following release of the head arteries; whereas cats 

 55 (one occlusion) and 57 (five occlusions) never regained more than 

 10 mm. at the time of the return of respiration. Cats 53 (seven occlu- 

 sions) and 56 (four occlusions) occupied a rather intermediate position, 

 never showing an increase of more than 20 mm. pressure during 

 recovery of bulbar function. 



No change in the time needed for the return of medullary activity, as 

 determined by the return of respiration and ocular reflexes, was noted 

 in these animals. As in the control series of repeated occlusion in 

 intact animals, this was not different after ligation of the adrenals from 

 that obtained in the fresh animal. Periods of recovery of from 10 to 

 20 minutes were recorded, being fairly constant for the given individual. 



No significant decrease in the anemic increment was observed, in 

 cats 53 (seven occlusions) and 57 (five occlusions) where increments of 

 120 to 140 mm. were obtained just prior to failure. These were oddly 

 enough the smooth curves recorded under early collapse. A much 

 more pronounced decrease in the anemic increment was shown in the 

 other animals in which more occlusions were obtained; in cat 52, 

 (eight occlusions) the last occlusion recorded showed an increment of 

 only 65 mm. 



The contour of the curves obtained is of considerable interest. Cats 

 53 and 56 immediately showed a single rise occupying about half the 

 original occlusion time (fig. 6), and this was a smooth unbroken curve. 

 Though the reduction in time was just as manifest in all the other cats, 

 the obliteration of the double nature of the curve was not so clearly 

 marked. In these cats the characteristic contour of the anemic rise 

 as seen in the fresh animal, merged gradually into the smooth curtailed 

 curve following adrenal ligation. The changes most evident were the 



