360 



Scientific Proceedings (123). 



they are subjected to C0 2 pressure for two or more hours. The 

 process may be repeated as often as desired although one treat- 

 ment, as a rule, is sufficient to effect emulsification. By repeating 

 the process several times a large percentage of the organisms may 

 be disrupted. After the C0 2 treatment the emulsion is diluted to 

 the desired standard with salt solution. In this way a perfectly 

 homogeneous suspension of tubercle bacilli, which gives no sedi- 

 ment after standing several days without agitation, may be ob- 

 tained. The addition of 0.2 per cent, trikresol enables the suspen- 

 sion to be kept in the laboratory indefinitely. 



We have performed the agglutination reaction on three hun- 

 dred cases, one hundred of which were known to have tubercu- 

 losis, and two hundred "normal" cases. With one exception all 

 of the tubercular cases gave agglutination. Of the "normals" 

 all but five gave a negative reaction. Of the cases five which gave 

 the positive reaction four were suspected of having syphilis but 

 only one of these had ever given a positive Wassermann. The 

 tests were carried out by the macroscopic method. The serums 

 were diluted 20, 40, 80, 160, 320 and 640 times respectively, 

 placed in the incubator for two hours, and in the ice-box over night. 



In this series of dilutions a proagglutinoid zone was noted in a 

 majority of the positive cases, in that agglutination was rarely 

 present in the tube containing serum in dilution of 1-20. Agglu- 

 tination was very marked, often complete precipitation, in dilu- 

 tions 40, 80, and 160 and somewhat irregular in the higher dilu- 

 tions. It is important that the serums used be free from hemo- 

 globin since we have found that hemoglobin causes a false agglu- 

 tination of the tubercle bacillus. From these results we believe 

 the agglutination test will prove of value in the diagnosis of 

 tuberculosis. 



175 (1922) 



Correlations among the constituents of potato tubers. 



By J. J. WILLAMAN and R. M. WEST. 



[From the Minnesota Agricultural Experiment Station, St. Paul, 



Minn.] 



It has long been known that both the total dry matter and 

 the starch content of potato tubers are proportional to the specific 



