180 EXPERIMENT STATION RECORD. 



Three one-year-old pigs which were fed for 13 weeks on peas and 

 potatoes yiekled on slaughtering from 150 to 105 lbs. of fat. The food 

 consumed contained at most not more than 25 lbs. of fat. In the same 

 way, 2 experiments by Boussingault with cows showed 1,050 gm. and 

 2,305 gm., respectively, of butter fat in the milk unaccounted for even if 

 it is assumed that all the fat in the food consumed was used for the 

 formation of fat in the body. However, it is a fact that considerable 

 quantities of the fat consumed are found in the excreta. 



Boussingault, Dumas, and Payen' again attempted to show that 

 sufficient fat was contained in the food of herbivora to account for the 

 fat formed in the organism. They reasoned that wax is formed by bees 

 fed only honey and sugar m just the same way that milk is produced 

 from the tissues of the body when the diet does not contain sufficient 

 fat and protein. In the other cases thej^ explained the fatty tissue 

 gained or the butter fat produced by the assumption of a higher fat 

 content in the food consumed. For instance, they used 7.59 per cent 

 for the fat content of maize, while Liebig considered it only 5 per cent. 



Boussingault made 2 new experiments- with cows. In the first, 7 

 cows were fed for one year upon hay. Assuming that it contained 1.8 

 per cent of fat, the amount consumed would furnish 089 kg. of fat. 

 The milk produced contained only 073 kg. of fat. Assuming that the 

 hay contained 2 or 3 per cent of fat, it would have furnished 700 or 

 1,149 kg., respectively. In the author's opinion, however, the hay con- 

 tained even more fat. In the second experiment a daily ration of straw 

 and roots furnished 1,110 gm. of fat to account for 915 gm. in the butter. 



The opponents of Liebig, however, were gradually compelled by their 

 own investigations to accept his theory of the formation of fat. This 

 was the case with Dumas and Milne-Edwards, who published their 

 investigations on the formation of wax by bees in 1843, They were 

 followed by Boussingault and Payen in 1845. 



Dumas and Milne-Edwards^ made their experiments with bees as 

 follows: The fat in the bees was determined at the beginning and end 

 of the experiment. The food consisted of pure honey or sugar. If 

 the bees did not draw upon their own tissues, wax must have been 

 formed from the sugar consumed. The first experiment did not sub 

 stantiate Liebig's view, since each bee produced only 0.5 mg. of wax, 

 although its body contained 2 mg. at the beginning of the exijeri- 

 ment. A second experiment, however, furnished a fine proof of the 

 correctness of Liebig's theory. A swarm of bees was fed honey 

 only for 32 days and produced 1L515 gm. of wax, although the honey 

 consumed contained only 0.607 gm. of fat. Each bee produced 0.0064 

 gm. of wax. The bodies before the experiment contained 0.0018 gm. of 

 fat and 0.0042 gm. at its close, and the weight of each bee had also 



•Ann. Chim. et Pbys., ser. 3, 8 (1843), p. 63. 



^Ann. Chim. et Phys., ser. 3, 14 (1845), p. 400; Compt. Rend., 17 (1843), p. 531; 

 Ann. Sci. Nat. Zool., ser. 2, 20 (1843), p. 174. 



