ENZYMES AND THEIR ACTION. 15 



called catalase which possesses the property of decomposing hydro- 

 gen peroxide. The presence of this enzyme may be demonstrated 

 as follows : Introduce into a low, broad, wide-mouthed bottle some 

 pulped liver tissue and a porcelain crucible containing neutral hydro- 

 gen peroxide. 1 Connect the bottle with a eudiometer filled with 

 water, upset the crucible of hydrogen peroxide upon the liver pulp 

 and note the collection of gas in the eudiometer. This gas is oxy- 

 gen which has been liberated from the hydrogen peroxide through 

 the action of the catalase of the liver tissue. 



B. Experiments on Anti-Enzymes. 



1. Preparation of an Extract of Anti-Pepsin. 2 Grind up a 

 number of intestinal worms (ascaris) 3 with quartz sand in a mortar. 

 Subject this mass to high pressure, filter the resultant juice and 

 treat it with alcohol until a concentration of sixty per cent is reached. 

 If any precipitate forms it should be filtered off 4 and alcohol added 

 to the filtrate until the concentration of alcohol is 85 per cent, 

 or over. The anti-enzyme is precipitated by this concentration. 

 Permit this precipitate to stand for twenty- four hours, then filter 

 it off, wash it with 95 per cent alcohol, absolute alcohol, and ether, 

 in turn, and finally dry the substance over sulphuric acid. The 

 sticky powder which results may be used in this form or may be 

 dissolved in water as desired and the aqueous solution used. 5 



2. Demonstration of Anti-Pepsin. 6 Introduce into a test-tube 

 a few fibrin shreds and equal volumes of pepsin-hydrochloric acid 7 

 and ascaris extract made as indicated above. Prepare a control tube 

 in which the ascaris extract is replaced by water. Place the two 

 tubes at 38 C. Ordinarily in one hour the fibrin in the control 

 tube will be completely digested. The fibrin in the tube containing 

 the ascaris extract may, however, remain unchanged for days, thus 

 indicating the inhibitory influence exerted by the anti-enzyme pres- 

 ent in this extract. 



3. Preparation of an Extract of Anti-Trypsin. 8 The extract 



1 Mendel and Leaven worth ; American Journal of Physiology, 1908, XXI, p. 85. 

 ' Anti-gastric-protease or anti-acid-protease. 



3 These may be readily obtained from pigs at a slaughter house. 



4 This precipitate consists of impurities, the anti-enzyme not being precipitated 

 until a higher concentration of alcohol is reached. 



5 The original ascaris extract possesses much greater activity than either the 

 powder or the aqueous solution. 



6 Martin H. Fischer; Physiology of Alimentation, 1907, p. 134. 



7 Made by bringing 0.015 gram of pepsin into solution in 7 c.c. of water and 

 0.23 gram of concentrated hydrochloric acid. 



8 Anti-pancreatic-protease or Anti-alkali-protease. 



