G. GENERAL NATURAL HISTORY AND ZOOLOGY. 235 



ous, and death speedily ensued (in four minutes for the bird, 

 and in twenty for the rabbit). 



The temperature in the rectum rose from 104 to 122 Fahr. 

 (bird), or 115 F. (rabbit), and the heart in both animals was 

 absolutely quiescent, while cadaveric rigidity was established 

 with extraordinary rapidity, and the arteries as well as the 

 veins contained black blood. The professor also verified the 

 experiments of Bichat in reference to the behavior of the 

 muscles of organic life and the striated muscles in resrard to 

 temperature, showing that the former are actually more sen- 

 sitive than the thermometer to slight variations of heat, any 

 increase of temperature actually calling forth peristaltic move- 

 ments in the intestines of a rabbit which had become quies- 

 cent after exposure to the surrounding air. This action is di- 

 rect, and is not communicated through the nervous system. 



The exciting action of heat, of course, has a limit, and this 

 is shown in the case of ^an animal exposed to a gradually ris- 

 ing temperature by the heart beating faster and faster, till at 

 length it stops, dead, with complete loss of irritability. The 

 cause of this cessation is, as Professor Bernard thinks, partly 

 chemical, and due to the coagulation of the santonin or my- 

 elin ; though, when life is prolonged for several days, other 

 causes, as yet undetermined, and affording a field for investi- 

 gation, co-operate. 13 A^ September 15, 1871, 441. 



EFFECT OF DIMINISHED PEESSUEE OX ANIMALS. 



In a memoir by Bert upon the influence exercised upon vi- 

 tal phenomena by variations in barometrical pressure, it is 

 stated that if the atmospheric pressure to w T hich a warm- 

 blooded vertebrate is exposed be suddenly reduced to fifteen 

 or eighteen centimetres of the barometrical scale, the animal 

 jumps about convulsively, is attacked with cramps, and dies 

 very quickly, w r ith bloody foam in the bronchia. Death oc- 

 curs with equal suddenness whenever the receiver under which 

 the animal is placed is closed, or is cut off from the external 

 atmosphere. In the first case the surrounding air is scarcely 

 changed, but in both cases the blood in the left cavity of the 

 heart is dark. 



On the other hand, should the pressure be diminished grad- 

 ually, and the air be continually renewed in the apparatus, 

 the animal can be kept alive for a long time. Should the 



