108 



Since the precipitate is soluble in alcohol, that which is obtained by filtering does 

 not represent all the hpematin, for a part would be dissolved while boiling. The 

 spectrum has one broad band near C. Most of the remaining portion of the 

 spectrum is also absorbed. 



If 95 per cent, alcohol be added to blood and a small quantity of caustic soda, 

 a still difTerent spectrum is obtained. This is the alkaline hjvmatin spectrum. It 

 is similar to the acid hiematin except the dark band is near and often on D. 



Effect of Heat Upon thk Irritability of Muscle. By A. J. Bigney. 



In these experiments tiie gastrocnemious muscle of the frog was used. It was 

 suspended in a moist chaml)er and the tendon attached to a lever for recording 

 movements in contraction on a revolving drum. Surrounding the cylindrical 

 moist chamber was another similar cylinder filled with water; near the bottom 

 was a small tube about one-half inch in diameter passing from it at right angles 

 and forming two sides of a rectangle, returned to the cylinder filled with water. 

 By this arrangement the water could make a circuit through this tube and the 

 cylinder. Heat was applied to the tul)e, and a thermometer was placed in the 

 moist chamber. 



The muscle was stimulated at difTerent temperatures and the result recorded 

 on the drum. Only making siwcks wei-e used in stimulation, this being regulated 

 by the automatic maker, or breaker. Between 36° and 38° C, the contractions 

 were the greatest, showing an increase in irritability. Between 39° and 40° the 

 contractions ceased, heat rigor having set in. At the time the contractions ceased, 

 the temperature was lowered and the muscle became irritable again. It would 

 continue irritable for some time, but would soon become exhausted. After several 

 hours' rest it would beconae quite irritable again. 



Heat rigor began to set in at a little more than 3(i°, sometimes not until 

 nearly 39°. It is different in different frogs and in different seasons. From 45° to 

 55° C. the rigor would usually be complete. The most important point to be secured 

 is that temperature at which contractions cease and still when the temperature is 

 lowered the muscle will be found to be alive so as to give contractions. When 

 the heat rigor would once begin, it would continue even if the temperature is 

 lowered. This holds true only for a few degrees. Long rest would allow it to 

 pass out of rigor if it had not gone too far. After at least 24 hours had elapsed 

 good contractions were obtained, and this with muscle that had once been ex- 

 hausted. 



