248 JOHN T. MYERS 



the sulphur is fully oxidized. Taurin was taken as a repre- 

 sentative of the sulphur components of proteins in which the 

 sulphur is fully oxidized. This compound is amino ethyl 



CH 2 NH 2 

 sulphonic acid I analogous to a sulphate except that 



CH 2 S0 3 H, 

 one oxygen is replaced by an H. It is also an amino acid. 

 Cystin the disulphide of diamino thiolactic acid was selected 

 because it is an amino acid. 



CH2S — S — CH2 



I I 



I I 



CH • NH 2 CHNH 2 



COOH COOH 



Here the sulphur is in the reduced state. Cystin is the usual 

 sulphur-containing amino acid found in proteins. Cystin and 

 taurin are analogous except as to the state of oxidation of the 

 sulphur. 



A medium was prepared as follows: ammonium tartrate 10 

 grams, anhydrous sodium sulphate, 10 grams, and distilled water 

 to 1000 cc. The mixture was put in culture tubes and auto- 

 claved for ten minutes at 15 pounds pressure. Five organisms 

 were used, B. coli and B. paratyphosus B, because they are hydrogen 

 sulphide formers which have no proteolytic action when tested in 

 the ordinary media, and B. fluorescens-liquifaciens, B. cloacae, 

 and B. proteus-vulgaris, because they are organisms, with varying 

 degrees of proteolytic activity. Duplicate cultures were made, 

 strips of sterile lead acetate paper were inserted in the mouth of 

 the tubes, and they were placed in a moist 37° incubator. No 

 growth appeared in any of the tubes at the end of seven days 

 incubation under aerobic conditions. 



An exactly similar medium to the one given above was made, 

 except that 10 grams of chemically pure glucose was added. 

 After seventy-two hours incubation a vigorous growth appeared 

 in all of the tubes but even after fourteen days incubation there 

 was no perceptible blackening of the lead acetate paper. Evi- 



