294 



THE KOTHAMSTED EXPERIMENTS. 



Fat again 

 shown to 

 be derived 

 from carbo- 

 hydrates. 



General 

 result. 



Voit criti- 

 cises the 

 Rotham- 

 sted results. 



To go a little into detail, it is seen that, for 100 increase in 

 live-weight, the amount of nitrogenous substance estimated to 

 be available for fat-formation was, in this series, intermediate 

 between that in the other two. With much less fatty matter 

 supplied in the food, the amount or fat estimated to be 

 newly-formed was about the same as in the other cases. The 

 amount of carbon estimated to be available for fat-formation 

 from the nitrogenous substance of the food was, in each case, 

 notably less than the amount required for the production of 

 the newly-formed fat. The indication is, therefore, that in 

 each case a considerable proportion of the produced fat must 

 have had its source in other than the nitrogenous constituents 

 of the food. 



The bottom division of the table shows that, reckoned for 

 100 carbon in the estimated newly-formed fat, in the first 

 case 18.9, in the second 18.8, in the third 25.2, and in the 

 fourth 14.1 per cent, or, on the average, about 20 per cent 

 of the whole must have been derived from other sources — in 

 fact from the carbohydrates. Nor can there be any doubt 

 that the figures under-estimate the proportion of the produced 

 fat which could not have had its source in the albuminoids of 

 the food. 



The general result of the whole series of experiments is, 

 then, that when the food of the fattening animal contains an 

 abnormally high amount and proportion of nitrogenous sub- 

 stance, enough of it will probably be available for the possible 

 formation of all the fat produced in the body ; but that, when 

 the amount and proportion of such substances in the food 

 are only normal, or low, there will remain a large proportion 

 of the produced fat which could not have had its source in 

 the proteids, and must have been derived from the carbo- 

 hydrates. 



Referring to our results and conclusions as given above, 

 Professor Voit, in a paper which he published in 1869, 1 admits 

 that in the experiments in which there was only a medium 

 albuminoid supply in the food, there was, as the figures stand, 

 a considerable deficiency for the formation of the fat produced, 

 and a still greater deficiency when the relation of the nitro- 

 genous to the non-nitrogenous constituents was lower still; 

 and hence it would appear that in these instances a con- 

 siderable amount of fat had been derived from the carbo- 

 hydrates. Still, he says, he cannot allow himself to consider 

 that a transformation of carbohydrates into fat is proved 

 thereby. He says he has not been able to get a clear view 

 of the experiments from the figures recorded, and suggests 



1 Zeitschrift fur Biologie, Band 5. 



