PERFORMANCE OF THE EXPERIMENT 185 



sufficient. As this method has not yet been applied 

 to large quantities, the most suitable time has yet to 

 be actually found. 



Exact comparisons are only possible, when the 

 test-tubes are of the same dimensions and have 

 exactly the same thickness. For this purpose we 

 must always arrange to have a sufficient stock of test- 



o 



tubes answering perfectly to this requirement. In 

 order to realize the importance of this proceeding, we 

 only have to pour a slightly bluish solution into a 

 wide and a narrow test-tube respectively, when we 

 see that the former will show a much deeper blue 

 colour than the latter. A faulty diagnosis would 

 thus result. 



The following cases are possible. The usual 

 result of the reaction is either, dialysate of serum 

 and of serum + organ negative, in which case 

 no decomposition has taken place ; and, if placenta 

 had been used, we should assert that there was no 

 placenta in the living state that had any connection 

 with the particular organism ; or else serum alone 

 gives negative, and organ - serum positive, results. 

 The diagnosis would indicate pregnancy, or, better 

 still, the existence of a placenta that still stands in 

 effective relations with the organism of the mother. 



o 



It may happen that the serum alone gives off sub- 

 stances to the dialysate, in sufficient quantity for the 

 positive reaction to appear under the conditions 



