12 



Scientific Proceedings (55). 



many variations of detail occur every record gives evidence of more 

 than an evenly rounded top. During the period of cardiac 

 ejection, the curve rises slowly and reaches a rounded summit 

 and the wave slowly declines until the movement of cardiac 

 relaxation, after which a sudden and abrupt fall occurs. When 

 curves are written with too sensitive manometers the flattened 

 top is less apparent to the eye, while, if also written on slowly 

 moving paper as was done by Straub, this top fades to a mere 

 suggestion requiring careful scrutiny to detect. 



The results, therefore, corroborate the work of Piper and C. 

 Tigerstedt that, during the systole of normal beats, a more or less 

 flattened top (plateau ?) occurs while the records of Straub are 

 not clearly typical because they were too large for the pressure 

 change and written on too slowly moving paper. With periodic 

 manometers vibrations are superimposed on the ascending and 

 descending limbs but these are either lost when the manometer is 

 aperiodic or so sensitive that a very large record is written. 



6 (823) 



A comparative study of the Ehrlich and Salkowski tests for indol 

 production by bacteria. 



By I. J. Kligler. 



[From the Department of Public Health, American Museum of 

 Natural History.] 



One of the bio-chemical reactions extensively used for the 

 identification of bacterial types is the production of indol from 

 peptone in a peptone-water solution. Of the various tests that 

 might be used for the detection of that substance the one most 

 widely adopted in this country is the so-called Salkowski test 

 (H2SO4 + KN0 2 ). In Germany Bohme (1905) and in England 

 Marshall (1907) have found, after a comparative study, that the 

 Ehrlich reaction (Paradimethylamidobenzaldehyde + HC1) gives 

 more uniform and constant results. 



This study was undertaken in order to obtain further light on 

 the relative reliability of the two tests. Seventy-five organisms, 



