80 ATROPHY, DEGENERATION, PIGMENTATION, AND NECROSIS, 



in various forms of intoxication are somewhat different from those oc 

 cnrring in other parenchyma cells and will be described in the section 

 devoted to the Brain and Spinal Cord. 



Cells in a condition of albuminous degeneration may return to their 

 normal state, they may become fatty or they may die, become uecrotic 

 a'nd disintegrate. 



The liver, kidney, muscle, mucous membranes, etc., when in this con- 

 dition, are often swollen and in gross appearance more opaque and gray 

 than when normal. 



The exact chemical nature of this degenerative process is obscure 

 and will doubtless remain so until we know much more than we now 

 do of cell structure and cell metabolism. 



TECHNIQUE. The microscopical study of this lesion is best made in fresh frozen 

 sections of the tissue, by the rapid formalin method, page 52 ; or in fresh tissue teased 

 in one -half -per-cent salt solution. 



FATTY DEGENERATION AND FATTY INFILTRATION. 



It is customary and convenient in considering the abnormal accumu- 

 lation of fat in the tissues to assume that in one set of cases fatty de- 

 generation the fat is formed by a retrograde metamorphosis or degen- 

 eration of the proteid elements of protoplasm, a process by which the 

 integrity and capacity of the cell are compromised ; while in the other 

 fatty infiltration it may be due to a simple accumulation in the cell of 

 fat formed elsewhere a condition of less significance. 



The validity of this assumption has of late been called in question. 

 It involves in large measure the solution of the physiological problem 

 whether normally the fat in the body is formed from proteids or from 

 carbohydrates. Concerning this many experiments and much argument 

 have been made ' ; but it appears not yet to be solved. The traditional 

 distinction between fatty degeneration and fatty infiltration will there- 

 fore be made here, with such modification and reserve as are fitting in 

 view of our lack of knowledge. 



FATTY DEGENERATION. 



In fatty degeneration there is an accumulation of larger and smaller 

 droplets of fat in the cell, sometimes so slight as to be scarcely visible, 

 sometimes so great as largely to replace the protoplasm, crowding the 

 nucleus to one side. These strongly refractile fat droplets are not 

 changed by dilute acetic acid. They are soluble in ether, and when fresh 

 are stained black by osmic acid (Fig. 16). Not infrequently, feathery 

 clusters of delicate fat crystals are present in the cells. Cells in exces- 

 sive fatty degeneration may disintegrate, forming an oily detritus in 

 which, especially when much moisture is present, cholesterin crystals 

 may form by decomposition of the fat. 



1 For a critical summary of this question, see Taylor, American Journal of the Med- 

 ical Sciences, vol. cxvii ., p.' 569, 1899. 



