16 THE EQUILIBRIUM OF COLLOID ANI> 



apparently loaded up with fat, demonstrate that the amounts of 

 Eat in the two cases are about equal. 



The normal liver tissue is capable of holding 5 to 10 per cent, 

 of fat in such form that it is quite transparent and invisible 

 in discrete form, being in fact an integral part of the bioplasm. 

 This can be done in no other way than by some type of union, for 

 a fraction only of this fat in free condition would give a thick 

 emulsion, showing obvious globules under the microscope, as it 

 does when conditions are interfered with as above described, and 

 the feeble union of the fat with the tissue broken up. 



Similar results are seen in the chemical phenomena accompany- 

 ing nerve degeneration. Again in the plasma or serum itself a 

 certain amount of union must take place, for, from a perfectly 

 clear serum, showing no oil globules whatever under the micro- 

 scope, as much as O g 5 to 1 per cent, of fat may be taken out by 

 organic extractives, such as alcohol and ether. Now this amount 

 of fat, were there no agency to hold it in clear solution, would be 

 sufficient to give a white milky emulsion. It is only when the 

 capacity of the serum for holding fat in solution by feeble union 

 with proteins is surpassed that the milky serum often found after 

 a heavy fatty meal is obtainable, and this excess of fat is so soon 

 taken into union by the bioplasm of the liver and other tissue 

 cells, that in an hour or two no trace of any microscopically visible 

 fat is seen in the serum or elsewhere. 



In this capacity of the serum for holding in union in invisible 

 form a certain amount of fat is found the solution of the problem 

 of fat transference in the body from one tissue to another without 

 any obvious carriage as an emulsion. By this power of solution 

 of fat in bioplasm is also provided the mechanism for the oxidation 

 of fats, for it is obvious that previously to oxidation the fat must 

 pass into simple molecular form, and that it cannot be oxidised as 

 globules of liquid fat. 



Apart from direct oxidation to furnish energy for the cell's 

 work, it is obvious that these lightly held unions of the organic 

 foodstuffs furnish the means for the chemical changes in the 

 cell which give rise to those syntheses of one organic body from 

 another which occur in animals as well as in plants ; for the 

 synthesis of new pro f eins by the union of protein radicles rich in 

 amido-acids with carbohydrate radicles ; for the synthesis of fats 

 from carbohydrates ; and for the elaboration of those products 



