1906.] 



On the Myelins, etc., of the Organism. 



363 



a further degree, and the fluid becomes perfectly isotropic without a sign of 

 double refraction. 



In this intermediate phase we deal with crystalline fluids, and the 

 individual crystals are fluid crystals, capable of being distorted by slight 

 pressure. We will not enter into the distinction between flowing, or 

 ductile, and fluid crystals, for the difference is purely one of degree. Nor is 

 it necessary here to discuss the opposing theories of Tammann and Quincke, 

 that the phenomenon is essentially due to the presence of two substances, the 

 truly fluid matrix and the suspended crystalline body. Schenck has demon- 

 strated by exact physical methods that it is capable of occurring with 

 absolutely pure bodies of this order. When the substances of this nature 

 are suspended in an inert matrix, upon passing from the solid to the 

 intermediate state or on being cooled from the isotropous to the intermediate 

 state the separate globules assume the form and characters of anisotropic 

 fluid spherocrystals. 



Towards the end of 1905 some 20 substance? of this nature had been 

 described. The majority of these are para-derivatives of anisol and phenetol, 

 with melting points considerably above 100° C. and " clearing points " (when 

 they become isotropic) from 20° to 300° C. higher (this last in the case of 

 silver iodide). Of more immediate interest is a series of acid esters of 

 cholesterin — cholesteryl oleate, cholesteryl benzoate, cholesteryl propionate — 

 and, for our purposes, of yet greater interest is the oleic acid group. The 

 cholesteryl soap we have already mentioned ; Schenck reports also the Na, K, 

 and NH 3 oleates, dimethyl and trimethyl NH 3 oleates. These have not been 

 so fully studied ; the very weakness of olein as an acid renders it difficult to 

 obtain the substances in a state of absolute purity, free from dissociation 

 products. Hence their " melting " and " clearing " points have not been 

 determined. 



Altogether, towards the end of 1905, some 20 of these crystalline fluids (or 

 potentially crystalline fluids) had been described. Their number is being 

 rapidly increased, Lehmann, in one of his test-papers, mentions one observer 

 as contributing a series of 10 new bodies. It will be seen that, employing 

 the formation of anisotropous spherocrystals as an index, we add a considerable 

 number — ammonium stearate and palmitate, cholesteryl stearate, palmitate 

 and butyrate, calcium oleate (?),* cholin oleate and possibly the lecithates of 

 K, Na, NH 3 and cholesterin. We mention these last tentatively. Very 

 possibly these bases dissociate the fatty acids from the lecithin, and the 



* We have here some doubt, but believe that the crystals here pass through a fluid, 

 perfectly globular state, before passing on to the solid spherolith state, which they are apt 

 to assume. 



