THE NATURE OF PROTOPLASM 309 



be fluid. It is clear, as well from all the observations which 

 we collected upon this point as from our theoretical concep- 

 tion and explanation of protoplasmic structure, that the in- 

 tervening substance must be interpreted as a watery solution. 

 With this interpretation Reinke's investigations, upon the 

 enchylema that may be squeezed out from ^thalium septicum, 

 are completely in harmony. With reference to the framework 

 substance our view requires, in the first place, that it should 

 be a fluid substance insoluble in water. It is clear that 

 this substance contains albuminoid bodies. From the most 

 recent observations it becomes more and more probable tEat 

 the principal component of the framework substance is 

 an albumen compound related to the nucleins, the so-called 

 plastin. Eeinke has interpreted the plastin, first clearly 

 recognised by him, in ^thalium septicum, and forming 

 according to his calculation 2 7 '4 per cent of the protoplasm 

 when dried in air, as a combination of albumen and 

 nuclein, possibly further accompanied by a number of mole- 

 cules of a fatty acid belonging to the stearic or oleic acid 

 series. In any case it results from these and numerous 

 micro-chemical observations of more recent times (compare 

 especially the works of E. Zacharias and Fr. Schwarz) that the 

 foundation of the framework substance is not an albuminous 

 body in the ordinary sense. All that we know of the pos- 

 sible nature of this substance is indeed very little, but 

 nevertheless enough for it to be not inconceivable to us that 

 it is insoluble in water, a fact still more intelligible if 

 Reinke's supposition, as to molecules of fatty acid entering 

 into its constitution, receive further confirmation. A series 

 of reflections, based upon an entirely different foundation 

 from Reinke's, led me to suppose, quite independently of his 

 speculation, which I did not know of till later, that the 

 chemical basis of the framework substance must be 

 formed by a body which has arisen from a combination 

 of albuminoid and fatty acid molecules. Since, as has 

 been said, it appears quite possible for such a body to 

 be insoluble in water, I hold the assumption of an oily 

 membrane or something of the sort, which would protect 

 it against the action of water, to be unnecessary; yet it 



