BARBER: HEREDITY IN CERTAIN MICRO-ORGANISMS. 



21 



consists of one solid piece of glass, there is no possibility of 

 leakage of air. 



In each of the five experiments, the results of which are 

 given in the table below, two similar fermentation tubes were 

 placed together, and one inoculated from a new race culture, 

 the other from a check ; and the two cultures supplying ma- 

 terial for inoculation were grown under similar conditions 

 long before the inoculation. In every case beef peptone broth, 

 plus the desired per cent, of sugar, was used, and each bulb 

 supplied with broth from the same lot and in the same quan- 

 tity, always 20 cc. The same new race, one originating about 

 November 1, 1903, was used in all five experiments. 



Table I. 



♦In this experiment broth was used to which lactose had been added after a previous 

 fermentation with Coli communis. Good growth was observed in the bulbs, but no gas was 

 formed. 



It will be seen from this table that the amount of gas pro- 

 duced by each type was nearly the same except in the two- 

 per-cent. saccharose test of June 16. Several readings were 

 made daily while fermentation was going on actively, and 

 these show that fermentation began in both types at about 

 the same time, rose at nearly the same rate, and reached its 

 maximum at about the same time. After the maximum had 

 been reached, the water in the graduated tube began to rise 

 again, due to the resorption of gas by the water and the nu- 

 trient fluid. The rate of resorption was more rapid in 

 the check than in the new race, in all except the one-per- 

 cent, glucose experiment. Since the amount of absorbing 

 surface is practically the same for each tube, and since the 

 check formed as much or more of a pellicle likely to obstruct 

 absorption than the new race, it is probable that in all ex- 



