PROTOPLASM 



11 



II. Structure of Protoplasm. 



Protoplasm occurs as a semifluid transparent viscous 

 material, usually in small individual particles — Cells — more 

 or less associated. It may, however, occur as larger con- 

 fluent masses — Plasmodia. 



Protoplasm in its simplest state may be regarded as a 

 fluid, since fine particles in it are seen to move freely in 

 Brownian movement (p. 13 (3)), and if it contains drops of 

 water they assume a spherical form ; certain plasmodial 

 masses of protoplasm among the myxomycetes in which 

 granules exist may creep through cotton wool and emerge 

 without their granules, having actually filtered them off. 



(a) 



(b) 



{c) 



Fig. 2.— (a) Foam structure of a mixture of Olive Oil and Cane Sugar; 

 (6) Reticulated structure of Protoplasm ; (c) Reticulated structure 

 of Protoplasm after fixation in the cell of an earth-worm (after 



BuTSCHLl). 



But while protoplasm may thus be looked upon as 

 essentially a fluid, a reticulated appearance can frequently be 

 made out even in the living condition (fig. 2), and from this 

 it has been concluded, chiefly as the result of Biitschli's 

 investigations, that there is a somewhat more solid part 

 arranged like the films of a mass of soap-bubbles, with a 

 more fluid interstitial part, a sort of foam structure which 

 might be compared to an emulsion of oil in a colloidal gum 

 solution. A certain amount of organisation is thus present 

 in most protoplasm, and in certain cells this organisation 

 becomes very marked. This conception of the structure of 

 protoplasm leads us to regard each vesicle as a minute 



