FUNCTIONS OF MUSCULAR TISSUE. 323 



and being recovered again, when the supply of blood was restored. The recent 

 experiments of M. Brown-Sequard on this subject are still more satisfactory, as 

 showing that the contractility of muscles may be restored by the transmission 

 of aerated blood through them, after it has entirely ceased, and has even given 

 place to cadaveric rigidity ( 333). Thus he found that when he connected the 

 aorta and vena cava of the body of a rabbit which had been some time dead, and 

 in which the cadaveric rigidity had already manifested itself for between ten and 

 twenty minutes, with the corresponding vessels of a living rabbit, so as to re-es- 

 tablish the circulation in the lower extremities, the rigidity disappeared in from 

 six to ten minutes, and in two or three minutes afterwards the muscles contracted 

 on being stimulated. He has subsequently made similar experiments upon the 

 muscles of a decapitated criminal; the hand being selected as a convenient part 

 for the purpose. It was not until nearly 12 J hours after death, that all traces 

 of irritability had left the muscles; and the injection was not commenced until 

 45 minutes after this, cadaveric rigidity having appeared in the interval. About 

 half a pound of human blood, which had been defibrinated and freely exposed 

 to the air so as to acquire the arterial tint, was then injected at intervals for 

 about thirty-five minutes; ten minutes after the last injection, the greater number 

 of the muscles were found to be irritable ; and these remained so for two hours, 

 after which the contractility gradually departed, and was succeeded by cadaveric 

 rigidity. The blood which had been injected in an arterialized condition, issued 

 from the vessels quite dark ; and as this occurred over and over again, the change 

 of hue could not be attributed to anything else than the reaction between the 

 blood and the tissues. Similar experiments were made 27 hours after death, 

 upon the muscles of the foot of the same criminal; but with an entirely nega- 

 tive result, save that the blood which was injected returned of a considerably 

 darker hue. 1 



324. The influence of supply of Arterial blood upon the Muscles is twofold ; 

 it affords the materials for the nutrition of the tissue; and it furnishes (what 

 is perhaps more immediately necessary) the supply of oxygen required for that 

 metamorphosis of the tissue, which seems to be an essential condition of the 

 generation of its contractile force. As this oxygen is taken in through the 

 lungs, and as the greater part of it is thrown off (when united with carbon into 

 carbonic acid) by the same channel, we should expect to find a very close corre- 

 spondence between the amount of muscular power developed in an animal, and 

 the quantity of oxygen consumed in its respiration; and this is in reality the 

 case. We find, for example, that in Birds and Insects, whose respiration is the 

 highest, the muscular power is greater in proportion to their size, than in any 

 other animals. In the Mammalia and certain Fishes, that might be almost 

 called warm-blooded, it is only in a degree inferior. But in the cold-blooded 

 Reptiles, Fishes, and Mollusca, the muscular power is comparatively feeble; 

 though even here we trace gradations, which accord well with the relative quan- 

 tities of oxygen consumed. But in proportion to the feebleness of the power, 

 do we usually find its duration greater ( 319); so that it is not so immediately 

 dependent upon the supply of oxygen, in cold-blooded, as in warm-blooded ani- 

 mals. Thus, it is found that Frogs are still capable of voluntary movement after 

 the heart has been cut out, and can move limbs which are connected with the 

 trunk by the nerves alone; and that this power is not altogether due to the 

 blood which may remain in the capillary vessels, is shown by the experiment of 

 Miiller, who found the muscles still contractile, after he had expelled all the 

 blood, by forcing a current of water into an artery, until it escaped from the 

 divided veins. It seems probable that the Muscles of Organic life are less imme- 

 diately dependent upon a supply of arterialized blood, than are those of Animal 



1 "Gazette Medicale," 1851, Nos. 24, 27. 



