I06 ANDREWS. 



haps the lamellae of Biitschli's structure are utilised mechani- 

 cally and possibly chemically also in organized contractile 

 phenomena, they are not of prime importance. 



Since the living substance wherever examined, down to 

 the smallest subdivisions of interalveolar substance in which 

 change of shape can be detected, showed such optical and physi- 

 cal phenomena as characterised contractile changes in Biitschli's 

 structure when viewed with equally inadequate powers ; there 

 seemed no escape from the conclusion that just so far as this 

 must we associate with such phenomena, with such contractile 

 manifestations of the substance as such, structural changes like 

 those seen in gross on a basis of Biitschli's structure- 



New Structural Formula for Protoplasm, 



The facts as they appear to me, seem in mosaic to offer the 

 following tentative formula for the living substance. 



[loo^] Protoplasm is a very complex emulsion, having the 

 physical arrangement of a very finely subdivided, variably 

 viscid, foam, which characters are coextensive with the con- 

 tinuous element of all visible optical reticula. 



The substance which at any given moment forms in all sub- 

 divisions of the foam the continuous element, varies its vis- 

 cidity by some unexplained changes within its finer structure, 

 so that from a very fluid state it may almost instantly become 

 viscid to varying degrees, even to a semblance of true solidity. 

 It is subject to displacement by contraction activity which may 

 be rhythmically organized, or may be of a filose nature. Such 

 changes may affect all, or a part only, of visible reticula, so as 

 to form of the interalveolar substance simple or compound 

 fibrils, or threads, or plates, of a different physical and optical 

 quality. These having necessarily the course of the continuous 

 substance must form optical striae simple or branched, or an 

 optical reticulum, the arrangement of whose lines, but not 

 whose mass, is governed by mode of distribution of the emulsive 

 inclusions. 



The continuous substance is at any given moment the physi- 



1 The whole section should be read under the head of this bracketed number. 



