E. Hindlb and Lajos G(5zony 
229 
also contains antibodies which are able to produce poisonous substances 
when mixed with amniotic fluid, which, of course, contains placental 
albumins. 
Certain serologists hold the belief that these antibodies, which are 
capable of dissolving cells and destroying albumins, really act like diges¬ 
tive ferments, but Abderhalden was the first author to show definitely 
that the injection of foreign substances into the blood may be followed 
by the production of ferments which dissolve them. Previously, 
however, Wohlgemuth had shown that the injection of amylum into 
the blood of a dog was followed by a considerable rise in the amylase 
content of the serum. 
Abderhalden’s first experiments were made with dextrose. W’hen 
he injected this substance intravenously into a dog, after an interval 
of two days the dog’s serum was able to decompose dextrose, this 
decomposition being observed by means of the polariscope. After a 
few days, however, the serum lost this power. 
Similar results were obtained by injecting silk-peptone into a dog, 
but the serum of this animal dissolved not only silk-peptone, but also 
albumose and other kinds of peptone. In other words the proteolytic 
ferments produced by the organism were not specific in this case. 
It was a matter of some surprise, therefore, when Abderhalden 
discovered that the serum of pregnant women contains proteolytic 
ferments which are very specific in their action, dissolving only the 
peptones and albumins contained in placental tissues. These ferments 
do not destroy any other kinds of peptones and, moreover, are only 
found in the serum of pregnant animals. 
In order to discover the presence of proteolytic ferments in the 
serum of any particular species, two methods have been employed. 
(1) The more exact method depends upon the fact that poly- 
peptids produce optically active solutions, which rotate the plane of 
polarised light to the left. Accordingly, a solution is prepared of the 
polypeptids from the placenta, or other organ to be tested, and mixed 
with the serum containing the ferments. Then the optical activity of 
this mixture is measured at once by means of a polariscope, and after 
two or three hours measured again. If the serum contains any ferment 
having an action upon the polypeptids employed, there will be an alter¬ 
ation in the optical activity of the mixture and this can be measured very 
exactly. In the case of pregnant women it is found that their serum, 
when mixed with polypeptids from a placenta, produce a decided 
change in the optical activity of the solution. The only objections 
