THE FORMATION OF FAT IN THE ANIMAL BODY. 181 



increased 0.106 gm. According to this, each bee must have produced 

 0.0084 gin. of wax from lioney. 



On the ground of some experiments in fattening a goose, which he 

 published in 1844, Persoz also concluded that fat was formed from car- 

 bohydrates. Persoz fed geese maize and they accumulated more fat 

 than the maize contained. He also fed geese food containing very 

 little or no fat — for instance, maize with the fat removed, potatoes, or 

 starch and sugar — nevertheless the geese gained considerable fat. 



In spite of the experiments which had been made and criticised — 

 for instance, Gundlach and Huberts research on the formation of wax 

 by bees, Playfair's on the pro<luction of milk by cows, and Persoz's on 

 the fattening of geese — Boussingault ' made new experiments on the 

 formation of fat with swine, geese, and ducks. 



A pig was fed from birth until it was 8 months old on i)otatoes, skim 

 milk, rye meal, and swill. The food contained 6.72 kg. of fat. At birth 

 the pig's bod}^ contained 0.65 kg. of fat, and at the end of 8 months, 

 15.48 kg. ; that is, 14.83 kg. of fat had been formed, although the food 

 consumed contained only 6.72 kg., aside from the amount contained in 

 the mother's milk which the pig consumed during the first 5 or 6 weeks 

 of its Mfe. In another experiment 9 pigs in 98 days ])roduced 43.6 kg. 

 more fat than was contained in the food consumed. In a third experi- 

 ment 6 geese, which were fed on maize, produced in 31 days 3,290 gm. 

 of fat which must have been formed from the starch of the food. 



Following this, Payen, the last of Liebig's opponents, declared his 

 belief in the formation of fat from carbohydrates, and pointed out the 

 experimental errors which had prevented the discovery of the truth 

 for so long a time. 



This closes the first period of the history of the question of the for- 

 mation of fat. It will be seen that in this period practically the same 

 theories were held which are held to day — a half century later. This 

 standpoint, correctly pointed out by Liebig, was, however, not reached 

 without much opposition from Voit and his followers. 



Two decades (1845-1865) intervene between the work of Liebig and 

 Voit. During this time the formation of fat from carbohydrates was so 

 thoroughly believed in that more feeding experiments along these lines 

 were not deemed necessary. The only important investigations were 

 those of Eobert Thomson (1847) and of Lawes and Gilbert (1853 and 

 1862). In studying the effect of various rations on the yield of milk 

 and butter, Thomson^ observed that the amount of butter increased 

 with the increased consumption of nitrogenous food. He concluded 

 that this "was due to some other cause than chance." Lawes and Gil- 

 bert's work will be discussed later. 



Aside from these agricultural experiments the question of the forma- 

 tion of fat was touched upon in a few experiments which were made for 



'Ann. Chim. et Phys., ser. 3, 14 (1845), p. 419; Compt. Eend., 20 (1845), p. 1726. 

 -Ann. Cheni. und Pharm., 61 (1847), p. 228. 



