( 482 ) 



exhibited the most brilliant interference-colours, which is also the case 

 with the cholesterol esters (acetate for instance), which possess labile 

 anisotropons liquid phases. The thought naturally at once occurred, 

 to attribute these phenomena to the appearance of liquid crystals in 

 the now pure «-phytosterol-ester. A similar behaviour was also 

 shown by perfectly pure a-phytosterol-acetate, but with a much less 

 display of colours. It was, however, a remarkable fact, that a-pkytO' 

 sterol-propionate even after complete solidification still retained those 

 colours for an indefinite length of time, particularly at those sides of 

 the testtube, where the layer of the substance was thinner and had 

 cooled rapidly. 



The microscopic investigation now showed that these two sub- 

 stances exhibit extremely rapidly disappearing anisotropous liquid phases 

 or, more probably, none at all 1 ); but that the said colour-phenomenon 

 is caused by a very peculiar spherolite-structure. 



In what follows, I have given the description of the solidifying 

 phenomena of the a-propionate, and also a figure representing the 

 typical structure of the fused and then cooled compound, such as is 

 present at the coloured sides of the tube. 



If a little of the solid substance is fused 

 on a slide to an isotropous liquid the fol- 

 lowing will be noticed on cooling. The 

 mass solidifies completely to spherolites, 

 namely to a conglomeration of circular, 

 concentrically grouped figures, which appear 

 connected with a series of girdles. When 

 three spherolites meet, they are joined by 

 means of straight lines which inclose angles 

 of about 120°. 



The mass is slightly doubly-refracting 

 and of a greyish colour; the rings and girdles are light greyish on 

 a darker back-ground. Each spherolite exhibits besides a concentric 

 structure, the black cross, but generally very faint. The whole 

 resembles a drawing of polished malachite from the Oeral, or of 

 some polished agates. 



] ) Whereas the pkytosterol-asievs, from Calabar fat which, of course, contain 

 a definite amount of the |3-homologue, exhibit no liquid crystals, the pure a-esters 

 commencing with the butyrate [or perhaps the propionate] did show this pheno- 

 menon. This discovery is a powerful argument against the remarks often made 

 in regard to the cholesterol '-esters, that the remarkable phenomena described are 

 attributable to an admixture of homologous cholesterols. Foreign admixtures 

 prevent as a rule these phenomena altogether ; in any case they are rather spoiled 

 than improved. 



Fig. 2. 



