SPECIFIC FERMENTS OF THE CANCER CELL 433 



While the globulins are filterable this does not prove that 

 the ferment is a globulin, but only that it filters through 

 with the globulin. The enzyme itself may be of much 

 simpler construction. 



In conclusion I may state that the most valuable deduc- 

 tions to be drawn from the work as so far conducted are 

 as follows: 



1. Transitory sensitization. The fact that an animal 

 may be sensitized to certain proteins, and that such sensi- 

 tization is active for only a few hours is of extreme interest 

 and importance. 



2. The active transitory ferment formed by the intro- 

 duction of cancer protein into an animal is not an albumin. 

 It is either a globulin or of simpler chemical structure. 



3. Sensitization, in the use of leukocyte extract at least, 

 is probably caused by the albumin content of the solution. 



Other Methods Used. In order that a more definite 

 knowledge of the chemistry of this specific ferment might 

 be obtained, the following experiment was made: 120 c.c. 

 of sensitized leukocyte extract, after filtration through a 

 Berkefeld filter, was mixed with an equal volume of satu- 

 rated ammonium sulphate solution. This was allowed to 

 stand overnight and the precipitate was then filtered off. 

 The precipitated globulins, while still slightly moist, were 

 removed from the filter paper and dissolved in a saturated 

 solution of sodium chloride. This was next rendered slightly 

 acid with 0.25 per cent, acetic acid, which again precipitated 

 the globulins. When the precipitation was complete and 

 had settled to the bottom, for which twelve to twenty-four 

 hours should be allowed, the globulin was collected upon 

 a hard filter paper. From this it was removed, while still 

 slightly moist, to a sterile watch-glass, where it was allowed 

 to dry. The globulin was next weighed and dissolved in 

 normal saline solution in the proportion of 1 mg. of globulin 

 to 1 c.c. of normal saline. 



The above method is given after using many different 

 modifications of the same. In many experiments I have 

 precipitated the globulins with semisaturated ammonium 

 28 



