120 



Prof. J. A. MacWilliam. On the 



[Oct. 24, 



A slender tendon (cat) was found to show extensive shortening at 

 about 63°. Hermann* found that tendon began to contract at 65° 

 .and finished at 75°. Brodie and Richardson f describe the contraction 

 as beginning at 60° and being complete at about 64°. 



GottschlichJ found that a piece of ligamentum nuchse shortened on 

 heating and lengthened on cooling for all temperatures up to as high 

 •as 65°. Another shortening, not removed by cooling, developed 

 between 65° and 75°. 



It may be mentioned that a frog's muscle tested with the apparatus 

 I have used for the arterial strips, shows very clearly the three heat- 

 contractions studied by Brodie and Richardson§ with the aid of a 

 photographic method at about 34°, at 45 — 50°, and at 55° — 60°, 



Contracted Artery. — "When an artery which is in a state of post- 

 mortem contraction is gradually heated, it undergoes a characteristic 

 change at a temperature of 50 — 55° C. — sometimes a little below and 

 sometimes a little above this level. It becomes relaxed, as is shown by 

 the tracing given by a transverse strip ; the rise of the lever indicates a 

 .marked elongation of the arterial strip (fig. 4) ; the same change is 



Fig. 4. — Carotid (ox). Transverse strip ; 25 hours p.m. Load under 1 gramme. 



evident in a piece of unopened artery by a notable enlargement of the 

 lumen, while the walls of the tube lose their firmness. When this relaxa- 

 tion has occurred, a subsequent lowering of temperature does not restore 

 the [contracted condition. Excitability and contractility are absent 

 after^the temperature has been raised to about 50°. It is important 



* * Pfiuger's Archiv ' (1873), vol. 7, p. 417. 

 t 4 Phil. Trans.,' B, vol. 191, p. 127. 

 t ' Pfiuger's Archiv 1 (1893), vol. 5 J, p. 109. 

 § Loc. cit. 



