16 NECROSIS OE TISSUES. 



§ 22. Having thus reviewed the various modes in which the 

 individual tissues break up, let us glance at the fluid which is 

 from henceforth their common rendezvous, and which may be 

 regarded as the organism in solution, though of course not in the 

 sense in which Molescliott has employed the phrase to designate 

 the blood. The composition of the sanies gangrenosa naturally 

 varies with its place of origin ; mortification of lung tissue will 

 obviously yield a fluid diftering in some respects fi'om that 

 Avhich results from gangrene of external parts. We may say 

 generally, that it has a foid odour and a loathsome greyish 

 yellow colour ; the latter assuming a rosy hue on the addition of 

 nitric acid, as was first noticed by Vircliow. Even its reaction 

 is not always alkaline. This, together with all the other differ- 

 ences exhibited by various specimens of the fluid, is due to 

 differences in its chemical composition, to which we will therefore 

 first devote our attention. 



§ 23. We have already seen that the putrefactive j^rocess 

 may physically be defined as a solution of the constituent ele- 

 ments of the body in water ; chemically, it may be viewed as a 

 new combination of the elements among themselves, and with 

 the oxygen of the atmosphere. Every chemical substance w^hich 

 enters into the composition of an organ is in a state of perpetual 

 tension; i.e. its atoms tend spontaneously to group themselves 

 otherwise than they are grouped. Life consists in their inabilit}' 

 to carry this tendency into effect ; their doing so is a sure sign 

 of death. A series of decompositions and recompositions ensue, 

 which differ for all the different constituents of the body, such 

 as albumen, fat, &c., but all of which ultimately issue in the for- 

 mation of carbonic acid, ammonia, and water. As this series of 

 phenomena is attended by a large consumption of oxygen, it 

 might be regarded broadly as a process of slow combustion 

 (eremacausis). The transitional compounds, of which there is 

 undoubtedly a great variety, are still to a great extent unknown. 

 Some are volatile, and when produced in abundance give rise to 

 the emphysematous variety of gangrene (Rauschhrand) ; they 

 cause the stench which offends our nostrils (sulphuretted hydro- 

 gen, ammonia, hydrosulphate of ammonia, valerianic and butyric 

 acids) ; others are non-volatile and soluble in water ; others 

 again are deposited in a solid form, so that after the complete 

 disappearance of the structural elements of the tissues, a new 



