FERMENT REACTIONS 307 



corresponding to the antiserum in question, i. e., of human blood, if 

 the antiserum was antihuman in character. To each tube, with the 

 exception of tube II (which is treated with 0.1 c.c. of normal rabbit 

 serum), 0.1 c.c. of the corresponding antiserum is then added in 

 such a manner that the serum flows down the side of the tube and 

 does not drop directly into the fluid below. The tubes are now 

 allowed to stand at room temperature and without shaking for 

 twenty minutes, when the final reading is made. If the result is 

 positive, i. e., if the suspected material was of human origin, precipi- 

 tation will occur in tubes I and VI, while II, III, IV, and V remain 

 clear. 



With this method reliable results can be obtained, so long as the 

 material under examination contains albumins which are still cap- 

 able of undergoing solution, even though they be present only in 

 traces. Uhlenhuth and Beumer thus mention that they obtained 

 positive results with blood which had undergone putrefaction and 

 had been left exposed to the air for two years, as well as with dried 

 blood-stains which were more than fifty years old. 



FERMENT REACTIONS 



The Pregnancy Test of Abderhalden. This test is primarily based 

 upon the observation that the parenteral introduction of complex 

 foodstuffs of alien origin either leads to the appearance in the blood 

 serum of reaction products de now which are capable of causing the 

 change of such bodies, or it increases the quantity of corresponding 

 products which may normally be present. Rabbit serum has thus 

 no digestive properties for silk peptone, while the serum of an animal 

 that has been previously injected with such material is capable of 

 effecting its cleavage. Similarly we find that normal serum is incap- 

 able of bringing about the cleavage of cane sugar, while the serum 

 of an animal that has previously been injected with the carbo- 

 hydrate in question does this quite readily. Most extensive investi- 

 gations along these lines convinced Abderhalden that such a reaction 

 on the part of the treated animal is of invariable occurrence, and in a 

 general way this corresponds to our views regarding antibody forma- 

 tion, as set forth in the first part of this volume. Without entering 

 into the question regarding the possible identity of the antibodies 

 in the sense of Ehrlich and the digestive reaction products with 



