CAUSES OF FATTY MET A MOI! I'IKtsIS 409 



and li])<)i(ls in i-clls <:ro\vii in tlie presence of sudi steatogenetie poi- 

 sons as pliosphorns and Oleum pulegii has been observed by others,'*"''' 

 which indicates that free cells behave the same under the influence 

 of such poisons as the cells of the fixed tissues. 



Tlie jirocess of nninaskin<|- the masked fats is explained by M. H. 

 Fischer^'"' on a pliysical l)asis, as follows: The fats of the cells are 

 distributed as an emulsion in a h3'dration compound of water with 

 hydroi)hilic colloids, notably proteins and soaps. Such an emulsion 

 breaks down whenever the hydropliilic colloid is either dehydrated or 

 diluted beyond certain ranges. As the usual conditions that cause 

 fatty degeneration, such as poisoning with phosphorus, arsenic, etc., 

 or local circulatory disturbances with local acidosis, all tend to de- 

 hydrate some of the cell colloids and to dilute others, it would seem 

 probable that the appearance of the fat droplets in the cells is the 

 result of such changes in the colloids that previously held them in an 

 emvilsion too fine to exhibit readily visible fat particles. The relation 

 of cloudy swelling to fatty degeneration is readily explained on this 

 basis, as follows: When a local acid intoxication of a cell occurs, 

 some of the proteins will swell and others will precipitate, resulting 

 respectively in the swelling and cloudiness of the cells characteristic 

 of cloudy swelling; but at the same time the emulsifying capacity of 

 these proteins will be impaired, penuitting the coalescence of the fat 

 droplets and the resulting picture will be that of fatty degeneration. 



Summary. — Fatty metamorphosis involves changes of two kinds. 

 First, infiltration of fat, which occurs when the oxidative power of 

 the cells is decreased, so that fat is not destroyed, but is accumulated 

 from the blood under the influence of the lipase of the cells; if there 

 is not any serious injury to the cells, the histological changes consist 

 in the accumulation of one or a few large droplets of fat in each cell, 

 constituting the condition known anatomically as "fatty infiltration." 

 This occui*s, pathologically, chiefly in the liver. If at the same time 

 the cytoplasm is disintegrated through autolytic changes, the fat- 

 droplets do not fuse, but remain as small, more or less discrete, fat 

 granules among the granules of cell debris, constituting the micro- 

 scopic picture of "fatty degeneration"; this condition occurs partic- 

 ularly in the heart and liver. 



Second, each cell contains a large amount of fat and lipoids (5-25 

 per cent, of its dry weight), which is so combined that it cannot be 

 detected microscopically ; this may be liberated during the autolytic 

 processes and colloidal changes of cell disintegration and become 

 visible, constituting a macroscopical and microscopical degeneration, 

 but without any actual increase in fat — this condition occurs partic- 

 ularly in the kidney and nervous system. Third, a combination of 



35b Krontowski and Poteff, Beitr. path. Anat., 1914 (58), 407. 

 35C Fischer and Hooker, Science, 1916 (43), 468; Fischer, Fats and Fatty Degen- 

 eration, Wiley, New York, 191". 



