poids (also known as lipofuscins, ceroid, etc.) are formed in vivo. Chro- 

 molipioids tnay be deposited: a) physiologically in some organs with slow 

 accumulation. This déposition was shown to be due to active metabolism, 

 and the increased oxygénation which is the rule in active metabolic states 

 is probably responsible for the formation of the lipid pigments; b) in 

 tissue damage with or without hemorrhage, where the hemoglobin or other 

 oxygen transport Systems accelerate oxidation; c) in cases of poisoning 

 by heavy metals, such as lead, bismuth, iron, thallium and copper, where 

 the heavy metals serve as oxidation catalysts; d) in relative or absolute 

 deficiency of anti-oxidants (mainly of vitamin E) in relation to the degree 

 of nnsaturation of the body fats. This occurs in expérimental avitamino- 

 sis E, if the animais are fed a diet rich inunsaturated lipids, and in con- 

 ditions associated with déficient absorption of this vitamin; e) from extra- 

 neous unsaturated fat introduced into the body, which is locally oxidized, 

 as in some lipid pneumoniàs or in sites of lipid injections. 



Différent lipids may be oxidized and polymerized to form chromolipoids. 

 The histochemical characteristics of the polymers differ, therefore, in ac- 

 cordance with the nature of the monomer, and also with the degree of po- 

 lymerization. Most chromolipoids are sudanophilic, give a positive P.A.S. 

 reaction because of the présence of 1—2 hydroxyls, are basophilic and 

 acid fast because of the numerous carboxyls, and are fluorescent. The 

 lower polymers are more soluble in lipid solvents, stain better by the 

 performic (or peracetic) acid Schiff procédure and by the carbonyl and 

 peroxide techniques than the higher polymers. Some chromolipoids are 

 also stained by Feulgen's nucleal technique probably because of bound 

 carbonyls. 



In conclusion, the plasmal and the other carbonyl techniques stain 

 mainly if not solely unsaturated lipids and their oxidative products. 



- 103 - 



