CRYSTALLOID IN LIVING CELLS 315 



fat, demonstrate that the amounts of fat 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, show- 

 ing 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 microscope, 

 as much as 0-5 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 

 food-stuffs 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 

 proteins by the union of protein radicles rich in amido- acids with 

 carbohydrate radicles; for the synthesis of fats from carbo- 

 hydrates ; and for the elaboration of those products of cell activity 



