1901.] Propert ies of the A rterial and Venous Walls. 



117 



markedly relaxed when it was rubbed between the finger and thumb 

 for a minute or two ; this relaxation passed off after a time. 



Somewhat similar results occur when a contracted artery is forcibly 

 stretched by the introduction of a glass rod 5 — 6 mm. in diameter. 

 Partial recovery may occur. Probably the arterial wall is injured by 

 the very considerable amount of force required to overcome its con- 

 traction in this way.* 



Effects of Heat upon Arteries and Veins and upon Saline Extracts. 



I have studied the effects of heat upon the arterial wall in different 

 ways — 



(1) By direct examination and measurement of portions of excised 

 artery, heated to various temperatures and at various rates while 

 immersed in defibrinated blood (of the same animal) or in olive oil, or 

 simply kept in a bottle or test-tube moistened with normal saline 

 solution. 



(2) By obtaining graphic records of the changes in length of strips 

 of the artery, cut either transversely or longitudinally, under the 

 influence of various temperatures. The arterial strip was placed in a 

 bath of olive oil, or defibrinated blood (when relatively low tem- 

 peratures were all that was necessary) ; the strip was rigidly fixed at 

 one end, while the other was connected (by means of a fine wire) with 

 a recording lever, suspended in the horizontal position by a long feeble 

 spiral spring, and writing upon a slow drum ; the bath was gradually 

 heated up by a spirit lamp or Bunsen burner, usually at about the rate 

 <of one degree Centigrade per minute, though the precise rapidity of 



* I have very recently found some references in John Hunter's writings, which 

 may be quoted in connection with the subject of post-mortem contraction. He 

 describes an experiment on the human umbilical cord, in which he found that 

 when the arteries wei-e cut across 2 days after delivery the lumen was found to be 

 closed 24 hours afterwards ; this did not occur when the section was made 3 days 

 after delivery. The experiment was performed on a portion of the cord left 

 attached to the placenta. Hunter also refers to the arteries being contracted after 

 death by haemorrhage : be speaks of the " stimulus of death," and describes the 

 "contraction by death" as being less in the aorta than in more distant vessels 

 (' Works,' London, 1837, vol. 3, pp. 158 and 168). In his ' Essays and Observations ' 

 (London, 1861), vol. 1, p. 133, Hunter mentions an experiment on the uterus and 

 its vessels : " I injected the uterus of a cow tbat had been separated from the 

 body of the cow about 24 hours ; and I found next day that it had contracted very 

 much, and that the vessels had also contracted, for the great trunks were more 

 turgid than when injected, so that the injection had been squeezed back again. 

 This also shows that the small vessels have a greater or longer power of contraction 

 than the large ones." 



In a footnote on the same page, Clift comments on the above experiment : 

 " May not this ' be the effect of elasticity in consequence of the parts having been 

 put into hot water while being injected? I have seen that happen." 



