FATS 183 



Later evidence in favor of the formation of fat from protein has 

 been furnished by the experiments of Weinland. This investigator 

 worked with the larvae of Calliphora, 1 these larvae being rubbed up 

 in a mortar 2 with Witte's peptone and water to form a homogeneous 

 mixture. After placing these mixtures at 38C. for 24 hours the fat 

 content was found to have increased, as much as 140 per cent in some 

 instances. The active agency in this transformation of fat is the larval 

 tissue, since the tissues of both the dead and living larvae possess the 

 property. Data are given from control tests which show that the action 

 of bacteria in this transformation of protein was excluded. Lusk 3 

 as the result of experiments on dogs claims to have definitely demon- 

 strated that fat may be formed from protein. 



EXPERIMENTS ON FATS 



1. Solubility. Test the solubility of olive oil ifl water, dilute acid and alkali 

 and in cold alcohol, hot alcohol, chloroform, ether, and carbon tetrachloride. 



2. Formation of a Transparent Spot on Paper. Place a drop of olive oil 

 upon a piece of ordinary writing paper. Note the transparent appearance of the 

 paper at the point of contact with the fat. 



3. Reaction. Try the reaction of fresh olive oil to litmus, Congo red and phe- 

 nolphthalein. Repeat the test with rancid olive oil. 4 What is the reaction of a 

 fresh fat and how does this reaction change upon allowing the fat to stand for some 

 time? 



4. Formation of Acrolein. To a little olive oil in a mortar add some dry potas- 

 sium bisulphate, KHSO 4 , and rub up thoroughly. Transfer to a dry test-tube 

 and cautiously heat. Note the irritating odor of acrolein. The glycerol of the 

 fat has been dehydrated and acrylic aldehyde or acrolein has been produced. 

 This is the reaction which takes place : 



CH 2 OH CHO 



OH -> CH+2H 2 0. 



II 

 ;H 2 -OH CH 2 



Glycerol. Acrolein. 



5. Emulsification. (a) Shake up a drop of neutral 8 olive oil with a little water 

 in a test-tube. The fat becomes finely divided, forming an emulsion. This 

 is not a permanent emulsion since the fat separates and rises to the top upon 

 standing. 



(b) To 5 c.c. of water in a test-tube add 2 or 3 drops of 0.5 per cent Na 2 CO 3 . 

 Introduce into this faintly alkaline solution a drop of neutral olive oil and shake. 

 The emulsion while not permanent is not so transitory as in the cases of water free 

 from sodium carbonate. 



l The ordinary "blow-fly." 



2 Intact larvae were used in some experiments. 



'Atkinson and Lusk: Proc. Nat. Acad. Sci., 5, 246, 1919; Lusk: Proc. Soc. Expt. 

 Biol. and Med., 17, 171, 1920. 



4 To prepare rancid olive oil add 5 drops of oleic acid to 10 c.c. of olive oil. 



5 Neutral olive oil may be prepared by shaking ordinary olive oil with a 10 per cent 

 solution of sodium carbonate. This mixture should then be extracted with ether and the 

 ether removed by evaporation. The residue is neutral olive oil. 



