March 31, 1916] 



SCIENCE 



471 



example, how smaller or larger amounts of fat 

 may be stored in cells without at one time 

 being visible or demonstrable by micro-chem- 

 ical methods, while at another, as in " fatty 

 degeneration," they are. 



There is scarcely a tissue or fluid of the 

 body which even in the poorest states of nu- 

 trition, does not contain some fat. But even 

 the smallest amounts of fat thus found exceed 

 the quantities that can be dispersed in perma- 

 nent form in pure water. The presence of 

 such amounts of fat in these structures, 

 therefore, at once presents a problem identical 

 with that which asks how it is possible, outside 

 of the body, to maintain a fat in finely divided 

 form in an aqueous dispersion means. The 

 presence of any amount of fat in a cell or 

 tissue exceeding a fraction of one per cent, is 

 possible only hecause the tissues contain hy- 

 drophilic colloids. 



Looked at from another point of view, even 

 the smallest amounts of fat ever found in 

 cells suffice to prove that the cell contents are 

 not mere aqueous solutions of various salts 

 and non-electrolytes contained in a semi-per- 

 m.eahle hag, as is so generally believed by the 

 adherents of the osmotic conception of cell 

 constitution. 



How completely the notion that our cells 

 are filled with salt solutions must go to pieces, 

 becomes clearly evident when it is recalled 

 that certain of our cells and tissues contain 

 even normally some twenty-five per cent, of 

 fat and fat-like bodies. Thus, of a hundred 

 grams of nerve tissue, seventy grams are water, 

 and over twenty grams are fat. The re- 

 mainder is protein chiefly. Nerve tissue 

 and all tissues which, under normal or ab- 

 normal circumstances, hold such large quanti- 

 ties of fat are able to do so only because this^ 

 material is stabilized in a finely divided state 

 through the presence of hydrophilic colloids 

 (like proteins and soap) which hold the water 

 of the cells as a hydration compound. 



While the fat in the cells of the body is not 

 ordinarily visible in the state in which it ex- 

 ists here normally, certain pathological condi- 

 tions popularly termed " fatty infiltration " or 

 "fatty degeneration" suffice to make the fat 



readily visible. The older pathologists be- 

 lieved that more fat was thus visible for the 

 reason that the cells had come to contain 

 more (either because this had been brought to, 

 or stored in the cells) or because their protein 

 had been changed to fat. Modern studies of 

 the question have proved the last of these 

 possibilities to be entirely without foundation, 

 so that now both " fatty infiltration " and 

 " fatty degeneration " are at the worst held to 

 be nothing more than states in which an ex- 

 cessive deposition may occur. But quantita- 

 tive chemical studies have come to show that 

 even the worst types of fatty degeneration in 

 tissues may yield no fat figures lying beyond 

 the amounts commonly found in these same 

 localities under physiological conditions. In 

 the majority of instances chemical analysis 

 fails to show that the affected cells contain 

 any more than their normal fat content. In 

 essence, therefore, " fatty degeneration " no 

 longer represents a chemical, but a physical 

 problem, which asTcs how a given quantity of 

 fat usually so distributed in a cell as to be in- 

 visible, becomes re-distributed in such fashion 

 as to be readily visible. 



We believe this problem is identical with 

 that which asks how an emulsion of oil in 

 protein or soap (so fine that the individual oil 

 droplets can not be made out as more than 

 granules even with high microscopic magnifi- 

 cation) can be broken to the point where the 

 fat granules will coalesce to form more read- 

 ily visible droplets. As a matter of fact, de- 

 tailed study of the conditions which are neces- 

 sary for the production of typical " fatty 

 degeneration " in tissues shows these to be iden- 

 tical with those which lead to the breaking of 

 emulsions of the type of oil in alkali-casein, 

 oil in soap, etc. 



The various substances generally listed as 

 capable of producing a " fatty degeneration " 

 (phosphorus, lead, arsenic, mercury, alcohol, 

 ether, chloroform, diabetes, local circulatory 

 disturbances, intoxication with acids, etc.) are 

 all of them means by which the normal hy- 

 dration capacity of the soaps or of certain of 

 the proteins of the cell (as the globulins) is 

 markedly decreased. The matter is best illus- 



