COLLOIDS IN PROTOPLASM 



therefore, has many of the physical and chemical 

 characteristics of true solutions. On the other 

 hand, properties must be present in protoplasm 

 which are only found in suspensions. We see 

 that such a state of things is very favourable 

 for the action and counteraction of many sub- 

 stances in the narrow territory of the protoplasm 

 of one cell. Water is without doubt the medium of 

 solution in protoplasm. Many substances, chiefly 

 of the groups of protein bodies and carbohydrates, 

 form the mucous emulsion colloid which is the 

 fundamental mass of protoplasm. Protoplasm is 

 practically an albumin sol. We remember that 

 fatty substances are regular constituents of proto- 

 plasm. They are not soluble in watery mediums, 

 but they may be brought into the form of colloid 

 solution in water, either only into the stage of 

 suspension colloids, as we can see on shaking oil 

 and water together, or even into the stage of 

 emulsion colloids. The latter can be reached by 

 adding a trace of potassium carbonate to the 

 mixture of oil and water. It is sufficient to shake 

 the mixture for a very short time to form a milky 

 liquid of great stability, which can be filtered 

 without change. The physical properties of such 

 oil emulsions are the properties of emulsion colloids. 

 In protoplasm fats must be present in the form of 

 suspension colloids and of emulsion colloids. Other 

 substances insoluble in water must be present in 

 similar^forms. 



D 33 



