66 POISONOUS PROTEINS 



Abderhalden found that when placental tis- 

 sue is digested with the serum of pregnant 

 women diffusible digestive products are formed 

 and may be detected in the diffusate by the 

 biuret and ninhydrin tests. He explained this by 

 supposing that placental tissue in small amount 

 finds its way into the maternal blood, and that 

 this fluid acquires the property of digesting 

 placental proteins. Abderhalden believes this 

 to be a specific reaction and has proposed it as 

 a diagnostic test for pregnancy. This test has 

 been studied by many and while its significance 

 cannot be considered as finally settled the 

 weight of evidence seems to be that Abderhal- 

 den 's explanation is not correct. It seems from 

 the evidence now at hand that the placental tis- 

 sue absorbs the antiferments and the unop- 

 posed protease of the serum digests the protein 

 constituents of this fluid. 



The weight of evidence today discards the 

 idea of specific proteases in blood serum and fa- 

 vors the idea that certain antibodies exist in the 

 serum and when these are reduced in amount, 

 the nonspecific protease of the blood serum acts 

 upon its own protein constituents. It must be 

 admitted that this view is more in accordance 

 with some of the facts than the one which holds 

 that specific proteases are existent in the blood 



