60 THE CELL 



rate than that of the micellae for each other, and hence when the 

 envelopes have reached a certain size a condition of equilibrium, 

 the limit of the power of the body to swell up, is reached." 



When, however, by means of special methods of treatment, the 

 attraction of the micellae for each other is quite overcome, a 

 micellar solution is obtained. This solution is cloudy and opal- 

 escent, which is an indication that the light is unevenly refracted. 

 Nageli compares this with the slimy opalescent masses produced 

 when Schizomycetes are crowded together in large numbers. 



Nageli explains the differences, which Graham has described 

 as existing between crystalloids and colloids, by the statement 

 that in the former isolated molecules are distributed amongst the 

 particles of water, whilst in the latter crystalline groups of mole- 

 cules or isolated micellae are so distributed. Hence numbers of 

 the one group form molecular solutions, and those of the other 

 micellar solutions (such as egg-albumen, glue, gum, etc ). The 

 micellae themselves have considerable power of preventing the 

 substance from breaking down into molecules. Such a breaking 

 down is generally accompanied by chemical transformation. 

 Thus starch, after it has been converted into sugar, is capable of 

 forming a molecular solution, as is also the case with proteids and 

 gelatine-yielding substances after they have been .converted into 

 peptones. 



In organised bodies the micellae unite together to form regu- 

 larly arranged colonies, in which the individual micellae may 

 consist of similar or different chemical substances, and may vary 

 as to size and form ; further, they may unite in smaller or larger 

 groups of micellae within the colony itself. The micellae within 

 these micellar colonies appear as a rule to hang together in chains , 

 which further unite together to form a frame or network structure 

 with more or less wide meshes. In the gaps or micellar interstices the 

 water is enclosed. " Only in this manner is it possible to have a 

 firm structure, composed of a large quantity of water and a small 

 quantity of solid matter, such as is seen in a jelly." 



The water, which is contained in organised bodies, may be 

 found in three conditions, distinguished by Nageli under the names 

 water of constitution or of crystallisation, water of adhesion, and 

 capillary water. By the first are understood the molecules of 

 water, which, as in a crystal, are united firmly to the molecules 

 of the substance in a fixed proportion, thus entering into the 

 structure of the micella. 



