J. BRONFENBRENNER 1057 



tissue in vitro one can observe the appearance of products of the digestive activity of 

 these ferments. This observation is the basis of the so-called "Abderhalden reaction." 



THE PRINCIPLE OP THE ABDERHALDEN REACTION 



The principle of the reaction consists in the detection of the products of hydrol- 

 ysis when a suspected serum is brought in contact with a specially prepared specific 

 substratum. If a given serum exhibits digestive activity in the presence of placenta 

 protein, for instance, the reaction indicates pregnancy; if protein-split products appear 

 in the presence of tumor cells, one concludes that the donor of the serum harbors a 

 tumor, etc. 



Although the reliability of the results obtained by means of the Abderhalden re- 

 action has been often questioned, yet there exists in the literature a considerable 

 number of reports indicating that by means of this test helpful information has been 

 secured in a variety of conditions. Such conditions are, for instance, early pregnancy 

 and incipient neoplasms, various disturbances in the activity of the glands of internal 

 secretion, or of the nervous system, as well as syphilis, tuberculosis, and other infec- 

 tious diseases. 



OPTICAL METHOD 



As stated before, the test consists essentially in the detection of hydrolysis taking 

 place in vitro during the incubation of the suspected serum with a suitable substratum. 

 As many of the products of protein digestion are optically active, their appearance 

 in the solution results in changes of the optical activity of the latter, and thus permits 

 the detection of the digestive process. The test is made by mixing suitable proportions 

 of the suspected serum with the peptone obtained from the corresponding tissue, and 

 at intervals observing the mixture in a polariscope. If the serum contains ferments 

 capable of attacking the given peptone, the plane of rotation undergoes gradual devia- 

 tion from the initial position. Because of the difficulty of preparing the soluble 

 substrata' and because of the necessity of employing special apparatus, this procedure 

 is not used extensively. 



DIALYSIS METHOD 



The procedure adopted by the majority of workers takes advantage of the diffusi- 

 bility of the products of digestion. If a serum, suspected of containing protective fer- 

 ments, is placed in a specially selected dialyzing shell, together with tissue (or other 

 substratum) presumably involved, these ferments react with the substratum and the 

 soluble products of the digestion diffuse out of the dialyzing shell into the outer fluid 

 The presence of specific ferments in the serum is thus indicated by the detection of 

 protein-split products in the dialysate by means of a color reaction (the ninhydrin 

 test). 



Reagents and apparatus: Serum. — Since the test depends on the appearance during the 

 reaction of dialyzable, ninhydrin-reacting substances, it is essential that such substances 

 should not be present in the serum before its incubation with substratum. In most cases the 

 concentration of such dialyzable substances in the blood is too low to complicate the test, but 

 under certain pathological conditions, in which excessive protein katabolism is involved 

 (as in cases of abscess formation, resorption of exudates or transudates, hemorrhages, 



' Abderhalden, E.: Handb. d. biol. Arbeitsmeth., 6, 223. 1913. 



