112 



Prof. J. A. MacWilliam. (hi the 



[Oct. 24, 



long as a fortnight after death ; a very slight residuum of contraction 

 has been found even IS days after death. 



Persistence of Excitability in Arteries after Death. 



The excised artery of a healthy animal kept at ordinary room tem- 

 perature either in defibrinated blood or simply in a bottle moistened 

 with salt solution, commonly reacts to certain modes of stimulation for 

 very many hours after death, often for 2 or 3 days. This is very 

 clearly evident when one makes a transverse incision across an artery 

 which has not shown much contraction after death, but has remained 

 with only a slight development of rigidity in its walls and with a rela- 

 tively large lumen (e.g., 4 — 5 mm.) ; soon after the arterial tube is cut 

 across contraction begins — slowly and gradually — to manifest itself, 

 the walls of the vessel become firm, and the lumen diminishes, so 

 that in 5 minutes the diameter may be reduced to about one-half 

 (2 — 3 mm.). In such cases decided contraction is usually evident in 

 a minute or two after the cut has been made., though it does not attain 

 its full development for some little time. 



Again, it is often seen that when an artery has gone into the con- 

 tracted state soon after death, it may relax to some extent in a day or 

 two, and then a fresh incision, 2 or 3 days after death, may lead to 

 well-marked contraction. This I have observed most frequently in 

 the arteries of the horse. 



Gentle manipulation of the artery with the fingers also tends to pro- 

 mote the development of the contraction. Strong galvanic currents 

 induce contraction. Faradic currents, unless very strong, have little 

 or no effect a day or two after death, when other forms of stimulation 

 are quite effective. 



Exposure to chloroform vapour is a powerful agency for causing 

 contraction. This is readily demonstrated by putting a piece of artery 

 into a tightly corked or stoppered bottle containing a little chloroform, 

 the artery being supported in such a position as to obviate any contact 

 with the liquid chloroform while it is freely exposed to the vapour. 

 When so treated, an artery which is only slightly and partially con 

 tracted a day or two after death shows a very striking change. Its 

 walls soon become firm, while its lumen becomes greatly contracted, 

 e.g., from a diameter of 4 — 5 mm. to one of 1*5 or 2 mm. j the surface 

 of the artery assumes a whitish appearance. 



The contraction so induced may persist for a long time or it may 

 diminish appreciably in an hour or two. In the latter case a fresh 

 exposure to chloroform vapour may again cause contraction. Much 

 depends on the length of time the chloroform vapour is allowed to 

 act ; prolonged action of chloroform induces a permanent change in the 

 arterial wall. 



