292 



Profs. Percy Frankiand and Marshall Ward. 



On carefully going over this table, which illustrates very clearly 

 the results of the struggle for existence between the two organisms, 

 it is evident (1) that both the anthrax and the Bacillus fluorescein 

 liquefaciens fall off in numbers day after day — for it cannot be urged 

 that the doubtful high number found on the sixth day invalidates the 

 general results — and (2) that the anthrax persists simply because it 

 passes into the spore condition. 



To make this last point quite certain, we heated a few c.c. of the 

 water to 54° C. for twenty- four hours, and then made new plates, with 

 the expected result : there were anthrax spores present. 



Possibly the third inference to be drawn from this experiment is 

 the most interesting of all, viz., that anthrax can hold its own in dis- 

 tilled water at 20° C, in the dark, not only in spite of the presence of 

 B. fluorescens, but (owing to its power of forming spores) it may even 

 tire out and exterminate the latter, because it cannot form spores in the 

 water. 



These results show with startling clearness how cautious we must 

 be in forming any opinions about the mutual relations between any 

 two bacteria, or, indeed, between any two organisms whatever. The 

 whole subject is a matter of biological experiment, and cannot be pre- 

 dicted on any other grounds than those of actual experiment. It is 

 very commonly supposed that a saprophyte like B. fluorescens lique- 

 faciens must be able to drive out a parasite like B. anthracis if the 

 latter invades the territory of the former ; the above experiment 

 shows that such is by no means the case under the conditions 

 afforded, and we onght to be very cautious indeed in surmising what 

 will occur under other conditions of the same general kind. 



In view of the facts above recorded, it seemed advisable to test the 

 question in another way, and we did this as follows : — 



A sterilised glass cylinder, A, receives a porcelain filter, B, also 

 sterilised, and held in position and protected from dust, &c, by a 

 covering and plug of sterilised cotton wool, C, and a paper cap. 

 After final sterilisation, the cylinders received about 300 c.c. of 

 Thames water, sterilised by filtration through porcelain. Bacillus 

 fluorescens liquefaciens was sown in the water inside the filter B, and 

 anthrax in the water outside the porcelain. Since experiments showed 

 that the green fluorescing liquid of the former passes readily through 

 such a filter, and that the excretions made by anthrax do the same, 

 it was hoped that this apparatus would help to answer the question, 

 Do either of these bacilli poison the water for the other ? 



The results, after twenty-four days' incubation at 20° C. in the 

 dark, proved that both the organisms were still alive, the anthrax 

 being chiefly or entirely in the form of spores. On heating the 

 whole apparatus up to 56° C. for twelve hours, the plates showed 

 total absence of B. liquefaciens fluorescens — proving that it developed 



