PROTAGON : LECITHIN : CHOLESTERIN 183 



egg yolk freed from cholesterin gave no myelin figures ; that 

 ordinary soaps on the addition of cholesterin gave them. In 

 other words, he produced experimentally impure cholesteryl 

 oleate, palmitate, and stearate. He called attention to the exist- 

 ence of cholesterin in tissues affording myelin and concluded 

 that in animal and vegetable tissues " ohne Cholesterin keine 

 Myelinformen." Liebreich retorted with his observations on 

 protagon, and Beneke's work became discredited. Neverthe- 

 less, Aschoff and I believe that Beneke, if too extreme in his 

 dictum, was largely right, and that in many situations in the 

 body the myelin globules are of the nature of cholesteryl oleate. 

 This, it may be noted, as shown by Hiirthle, is a constant con- 

 stituent of the blood. In the atheromatous patches in the aorta, 

 in old cataracts of the eye, and in other necrotic areas, it is a 

 matter of familiar experience that we encounter fatty globules 

 along with plates of cholesterin, and here, too, we meet with 

 the myelin globules. An incidental observation on an aorta 

 showing early atheroma impressed me greatly. The smear 

 from a small area of slight softening presented numerous fatty 

 globules and cholesterin crystals, but no doubly refractive 

 bodies. I heated it gently over the flame, and on cooling there 

 appeared abundant myelin globules, more particularly in the 

 neighbourhood of the cholesterin platelets, which now exhibited 

 a somewhat corroded appearance. Nay more, we would suggest 

 that cholesteryl oleate is the source of cholesterin calculi in the 

 gall-bladder. 



Cholesteryl oleate excreted from the blood into the bile (and, 

 as Virchow showed, myelin is present in the normal bile) may 

 in the alkaline fluid easily undergo dissociation, the oleic acid 

 combining to form simple diffusible soaps, the cholesterin being 

 set free. At the last meeting of the German Pathological 

 Association at Stuttgart, Aschoff demonstrated the presence of 

 the doubly refractive myelin globules in the cells of the mucous 

 membrane of the gall-bladder. 



We thus have what I regard as strong presumptive evidence 

 that at least two groups of oleic acid compounds give rise to the 

 myelin globules of the organism the cholin or neurin, and the 

 cholesterin. There is a third group deserving consideration, 

 namely, the lecithins. Regarding these I would speak with 

 considerable caution, while at the same time stating my con- 



