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THE POPULAR SCIENCE MONTHLY 



blood consists of a complex liquid, in which are suspended a multitude 

 of minute cells, some red, others colorless. When the blood is removed 

 and dies, it clots or partially solidifies, and is found to contain a net- 

 work of extremely fine fiber, to which the name of fibrin is applied. 

 A similar change takes place in the substance of the muscle after 

 death. It stiffens, and this stiffening, or rigor mortis, is effected by 

 the formation of a clot analogous to the coagulation of the blood, and 

 the substance of this clot (myosin) is so nearly like the fibrin of the 

 blood and the material of the muscular fiber (syntonin) that for our 

 purpose they may be all described as varieties of fibrin. 



The properties of fibrin, so far as cookery is concerned, place it be- 

 tween albumen and gelatine ; it is coagulable like albumen, and solu- 

 ble like gelatine, but in a minor degree. Like gelatine, it is tasteless, 

 and non-nutritious alone. This has been proved by feeding animals on 

 lean meat, which has been cut up and subjected to the action of cold 

 water, which dissolves out the albumen and other juices of the flesh, 

 and leaves only the muscular fiber and its envelopes. The same is the 

 case with the spontaneously coagulated fibrin of the blood ; it is, 

 when washed, a yellowish, opaque, fibrous mass, without smell or taste, 

 insoluble in cold water, alcohol, or ether, but imperfectly soluble if 

 digested for a considerable time in hot water. 



The following is the chemical composition of these three constitu- 

 ents of lean meat, according to Miiller : 



There are two other constituents of lean meat which are very dif- 

 ferent from either of these, viz., Kreatine and Kreatinine, otherwise 

 spelled creatine and creatinine. These exist in the juice of the flesh, 

 and are freely soluble in cold or hot water, from which solution they 

 may be crystallized by evaporating the solvent, just as we may crys- 

 tallize common salt, alum, etc. They thus have a resemblance to min- 

 eral substances, and still more so to some of the active constituents 

 of plants, such as the alkaloids, theme, and caffeine, upon which de- 

 pend the stimulating or " refreshing" properties of tea and coffee. 



Their chemical composition and general relations have suggested 

 the theory that they are the dead matter of muscle, the first and sec- 

 ond products of the combustion which accompanies muscular work, 

 urea being the final product. According to this, their relation to the 

 muscle is exactly the opposite of that of the albuminous juice, this 



