534 INFECTION AND RESISTANCE 



The earlier experiments with fats were negative because the 

 simple method of titration for fatty acids proved insufficient as an 

 indicator of activity. However, Abderhalden succeeded in determin- 

 ing fat splitting properties in the blood of treated dogs by using the 

 method of Michaelis and Rona. 30 The presence of fats largely in- 

 creases the surface tension of mixtures, and their cleavage in such 

 mixtures consequently leads to reduction of this tension. Utilizing 

 this principle, Abderhalden claims to have determined that the paren- 

 teral introduction of fats into dogs is followed by a reactionary in- 

 crease of lipases. 



The general significance of Abderhalden's researches is this: 

 When any foreign substances, protein, carbohydrate, or fats, gain 

 entrance to the circulation of an animal, the animal body reacts by 

 the mobilization of ferments or enzymes specifically capable of re- 

 ducing these substances to assimilable form. It is likely that these 

 ferments represent a mobilization of substances normally present but 

 not concentrated in the blood stream under ordinary conditions, since 

 they appear with a speed out of all proportion to that obtaining in 

 the case of the antibodies discussed in another place. In one case 

 cited by him a dog injected on November 25th, 29th, and December 

 4th showed powerful peptolytic serum properties on December 6th. 

 Apparently the injection of homologous proteins into animals (i. e., 

 rabbit serum into rabbits, etc.) does not incite reaction. 



These enzymes seemed to differ from specific antibodies in that 

 they did not react solely with the substance injected, but also with 

 other substances belonging to the same chemical group. Other dif- 

 ferences from antibodies are the rapid appearance of the ferments 

 after treatment and their rapid disappearance after the inciting 

 stimulus is removed. Thus Abderhalden reports that the enzymes 

 found in .a case of pregnancy disappeared within eight days after 

 abortion or child birth. 



It is plain that these researches of Abderhalden offer many op- 

 portunities for diagnostic utilization, and he has applied them to the 

 diagnosis of pregnancy. In this condition substances from the 

 -chorionic villi get into the blood. These, according to Abderhalden, 

 may be looked upon as in a certain sense foreign in nature, and must 

 be chemically disintegrated by the body. In consequence it is likely 

 that the ferments which accomplish this would appear in the sera of 

 pregnant individuals and could be determined by his methods. 

 "When he prepared peptone from the placental substances of human 

 beings and allowed the blood plasma of normal individuals to act 

 upon it, observing it both by the dialysis and the optical method, no 

 peptolytic action could be observed. However, when the plasma of 

 pregnant women was used proteolytic action was determined. In 

 these cases the ferment seemed to be specific for peptones produced 



30 Michaelis and Rona. Cited from Abderhalden, loc. cit. 



