128 



Scientific Proceedings (66). 



that method must create at first an unfavorable impression. 

 Nevertheless the observations tallied so remarkably with our own, 

 as to demand confirmation. The work, if correct, opens up such 

 a large field for research that the writer sought to verify it by a 

 similar series of experiments. 



In the absence of any details as to the method of preparing 

 the dry substrate, the following plan was adopted. 



Two placentas were obtained, freed from blood by washing 

 in saline solution, and then in running water, and treated according 

 to Abderhalden's directions until the water in which the substrate 

 had been boiled for five minutes gave no ninhydrin reaction. 



One half of this substrate was placed in a sterile jar containing 

 50 per cent, glycerine in water, covered with toluol and kept in 

 the ice-box; the other half was treated as follows: 



It was minced finely, dried in the oven at 8o° C. for 4 hours, 

 and then over-night at 55 0 C. Next day it was ground to a fine 

 powder in a sterile mortar and kept in a desiccator over calcium 

 chloride for 3 days. The appearance of the substrate is that of a 

 fine, dry, brown powder which can be kept in a closely stoppered 

 bottle without fear of autolysis or bacterial action. 



The use of animal charcoal as recorded by Kiutsi for the 

 purpose of removing bodies giving a positive biuret reaction was 

 found unsatisfactory. The method was slow and tedious, fresh 

 filters of charcoal had to be employed for every sample of urine, 

 and often the filtrate showed a purplish tint due to coloring 

 matters absorbed from the charcoal. As a substitute method, 

 shaking with kaolin was tried. Experiments were then conducted 

 to determine 



1. The amount of kaolin necessary to remove from the urine all 



bodies giving a positive biuret reaction. 



2. The optimum amount of dry substrate to be employed. 



3. The optimum incubation period. 



4. The effect of the acidity or alkalinity of the urine on the 



reaction. 



5. The effect of bacterial growth during the incubation of the 



urine to be tested. 

 As a result of these experiments the following method was 

 devised, and has been found to be satisfactory. 



