480 Mr. L. Hill. Oh Cereh^al Ancemia and the 



" On Cerebral Ansemia and the Effects which follow Ligation of 

 the Cerebral Arteries." By Leonard Hill, M.B. Com- 

 municated by Dr. Mott, r.K.S. Eeceived March 22, — Eead 

 May 17, 1900. 



(Abstract.) 



1. Cerebral Ancemia pvdAiced by Immobilisation in the Erect Fosture. 



Many hutch rabbits when immobilised in the erect postiure become 

 convulsed and after a short period of time die (10' — 20') from failure 

 of respiration.* 



The blood, owing to its weight, congests within the abdominal 

 vessels, while the abdominal ^dscera drag on and so kink the vena 

 cava inferior. The heart, therefore, gradually empties, and the cere- 

 bral circulation ceases. These results are due to the flaccid and 

 atonic natme of the abdominal wall of the hutch rabbits. Chloralisa- 

 tion hastens the onset of death by'dilating the arteries and by stopping 

 the convulsions, for the spasms help to return the venous blood to the 

 heart. Compression of the abdomen by a bandage, or immersion of 

 the animal in a bath of water up to the neck, entirely prevents the 

 onset of symptoms. In the case of the bath the hydrostatic pressure 

 of the water outside balances, but not completely, the hydi'ostatic 

 pressure of the blood within. At the same time the water causes the 

 viscera to float upwards, and so removes the kinking of the vena cava 

 inferior. 



Wild rabbits, owing to the better tone of their abdominal muscles, 

 are not affected by immobilisation in the erect posture until after the 

 lanse of some hours, and the same is the case in respect of dogs, cats, 

 and monkeys. When the tone of the skeletal and vascular muscle 

 becomes exhausted in these animals, owing to exposure, shock, &c., or 

 is abolished by ansesthetics, the blood congests to the lower parts. 

 Death finally results from cerebral anaemia. Immersion in a bath or 

 compression of the abdomen has the same restorative eff'ect on the circu- 

 lation of these animals as on that of the hutch rabbit. 



Intense congestion and oedema of the lower parts, accompanied by 

 thirst, is said to occl^r in men under like conditions, and death no 

 doubt results from cerebral anaemia. 



Hutch rabbits, when thrown into syncope by immobilisation in the 

 erect posture, recover almost immediately on their return to the hori- 

 zontal position, or on immersion in a bath, or on compression of the 

 abdomen. The animals when returned to the horizontal posture may 



* This fact was noted by Salatlie, 



