826 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



menced until 45 minutes after this, cadaveric rigidity having appeared in 

 the interval. About half a pound of human blood, which had been defibri- 

 nated 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, twenty-seven hours after 

 death, upon the muscles of the foot of the same criminal, but with an en- 

 tirely negative result, save that the blood which was injected returned of a 

 considerably darker hue. 1 Still more recent experiments have shown, that 

 in order that the muscles should retain their elongated condition, it is neces- 

 sary that they should be supplied with arterial blood, the passage of venous 

 blood through their capillaries immediately inducing contraction. This was 

 remarkably exemplified in an experiment made by M. Brown-Sequard upon 

 a pregnant rabbit, in which the injection of venous blood into the uterine 

 vessels immediately excited the organ to contract, and caused the expulsion 

 of two or three foetuses, whilst on injecting arterial blood all signs of con- 

 traction immediately passed off. It is doubtful whether the stimulus to 

 contraction in these cases is the presence of carbonic acid, or whether, as 

 Dr. Radcliffe 2 supposes, it is not rather to be attributed to a deficiency of 

 oxygen, the readmission of which restores the vital properties of the muscle 

 and induces its elongation. The latter view is certainly supported by the 

 violent convulsions which occur in animals that are bled to death; and even 

 the convulsions which are witnessed in asphyxia, when the contracted state 

 of the small arteries ( 324) and the consequent diminished transmission of 

 blood through the capillaries are borne in mind, are not unfavorable to it. 

 Dr. Radcliffe has adduced the interesting experiments of Dr. George Harley 3 

 upon the influence of the addition of strychnia and brucia to blood, as essen- 

 tially confirmatory of his view; since these poisons diminish the capacity of 

 the blood to absorb oxygen, and their action may thus be said to be equiv- 

 alent to a copious loss of blood. 



676. Whilst the Irritability of Muscles is gradually departing after death, 

 it not unfrequently shows itself under a peculiar form ; for, instead of pro- 

 ducing sudden contractions, speedily followed by relaxation, the application 

 of stimuli then occasions slow and somewhat prolonged contractions, the 

 relaxation after which .is tardy. This form of contraction is seldom seen in 

 adult Mammalia, except (as will be presently shown) when death has taken 

 place from certain diseases that have a special influence on the blood and 

 muscular system ; but it is stated by M. Brown-Sequard 4 to present itself 

 more constantly in young animals, and to be (so to speak) an exaggeration 

 of the ordinary modus operandi of their muscles, which during life are much 



1 In Robin's experiments upon decapitated criminals, the heart could be made to 

 recommence its rhythmical contraction by blowing air into its cavities upwards of 

 one hour and a quarter after execution. The contractions continued for eight minutes. 



Rosen thai (Wien. Med. Press, 1872, Nos. 18 and 19) found that the muscles of the 

 trunk and extremities lose their irritability and cease to respond to farado-electrical 

 excitation within a period varying from 90 to 180 minutes after death. 



2 In whose work on Epileptic and other Convulsive Affections of the Nervous 

 System (3d edit., 1861) much original and interesting information on the subject of 

 muscular contractility will be found. 



3 See Lancet, 18-56. 



4 Gazette Medicate, December 22d, 1849. See also Norris, loc. cit. 



