124 



Prof. J. A. Mac William. On the 



[Oct. 24 T 



time. Similarly the lengthening of the transverse strip about 40° and 

 between 50° and 60° is accompanied by a certain amount of shortening 

 of the longitudinal strip. Fig. 7 shows the relative behaviour of the 

 two strips when heated up to about 58°. 



But this converse relation ceases as the temperature rises ; both 

 strips contract markedly at 60 — 65°. 



(3) Another method of studying the influence of heat upon the 

 arterial wall is to use a segment of artery, one end of which is 

 closed by tying in a wooden plug, while into the other end is 

 fastened one extremity of a long glass tube of small bore. The 

 interior of the artery and the glass tube for part of its length are 



FlG. 7. — Upper tracing, transverse strip of contracted artery (carotid of ox). 

 Lower tracing, longitudinal strip of same artery. The phases of elongation 

 (35° — 45° and 50° — 58°) in the transverse strip are coincident with phases of 

 shortening in the longitudinal strip and vice versa. 



filled with olive oil, and a graduated millimetre scale is placed behind 

 the tube so that the position of the column of oil may be acurately 

 read off. The tube is bent at right angles not far from the artery, so 

 that the main part of the tube (with the scale) may be fixed in the 

 horizontal position while the artery is placed vertically in an oil bath, 

 the temperature of which is then raised in the usual way. Contraction 

 and relaxation of the artery are indicated by the advance or retreat of 

 the oil in the horizontal tube. The results are entirely confirmatory 

 of those obtained with transversely cut strips from the same artery. 



Effects of Temperature Changes on some other Unstriped Muscles 

 of Mammals. 



The behaviour of the contracted arterial muscle presents a notable 

 resemblance in many respects to what is seen in some other unstriped 

 muscles which have been examined in the living condition. 



The retractor penis muscle* retains its vitality long after removal 



* Eckhard, 'Eeitrage zur Anat. u. Physiol.,' vol. 3, p. 123 (1863) ; Langley and 

 Anderson, ' Journal of Physiology,' vol. 19, p. 85 ; Starling, in ' Schafer's Text- 

 book of Physiology,' vol. 2, p. 349 (1900) ; Sertoli, ' Archives Italiennes de 

 Biologie,' vol. 3, p. 78 ; Schultze, 'Arch, fur Physiologie,' 1896, p. 54. 



