FATTY DEGENERATION 389 



of oxygen in the tissues leads, as we have seen, to the accumulation 

 of acids. This, after death of the organism, .occurs in every tissue, 

 but it may also be demonstrated in cases where a particular 

 organ or region of the body is deprived of its quota of oxygen. 

 By the administration of certain drugs, e.g. anaesthetics, heavy 

 metals, phosphorus, potassium cyanide, oxidation processes are 

 inhibited and acids accumulate. The first visible change after 

 the inhibition of oxidation general or local is a " softening " 

 of the tissues concerned. If water is available the involved cells 

 swell and become cloudy accompanied or followed by a " yellow- 

 ing " and the appearance of fat globules. The cells then tend to 

 shrink and liquefy. These changes can be mimicked by the 

 addition of a trace of acid to an oil-in-protein emulsion. The 

 emulsifying colloidal proteins, under the influence of acid, develop 

 an increased capacity for the imbibition of water. If water is 

 available, the proteins swell and become extremely dilute and the 

 emulsion is broken. The " graying " or cloudiness is due to the 

 presence of colloids (globulins ?) which become less hydrated in 

 an acid solution. The hydration of the one class of colloids and 

 the dehydration of the other class leads to " cloudy swelling." 



The breaking of the emulsion sets free the fat which is present, 

 though normally invisible, in all cells. The tissue becomes yellow, 

 and as the pathologist s say, " fatty degeneration " has become 

 apparent. It must be understood that the fat made manifest 

 by this process existed previously in the cell masked by its associa- 

 tion with proteins, etc., in the emulsion. Its appearance at this 

 stage of dissolution is not due to the conversion of protein or any 

 other cell-constituent into fat as the name " fatty degeneration " 

 might suggest. Careful analysis has shown that the total amount 

 of fat in the cell has not increased. 



As an emulsion has a much higher viscosity than its consti- 

 tuents, one might expect that the breaking of the emulsion would 

 lead to a decrease in viscosity or softening of the tissue concerned. 

 Further changes take place which make this loss of rigidity more 

 marked and cause the ultimate dissolution of the protoplasm. 



Almost co-incident with the cessation of respirations, the endo- 

 enzymes begin to accelerate the processes of hydrolysis of the 

 tissues (p. 96). Under sterile and anaerobic conditions, the tissues 

 may be converted into an almost odourless fluid a process termed 

 autolysis. Proteins are broken down to their constituent amino 

 acids and, if autolysis is carried on sufficiently long, some of these 

 acids may be destroyed. Instead of fat, autolysed tissue contains 



