476 



Mr. J. C. Ewart on the Life-History of [June 20, 



lately found in scum from the surface of sea- water by being motion- 

 less. Those in the scum, notwithstanding- their length and the number 

 of spores in them, were moving freely about the field. 



Having satisfied myself that, under certain conditions, the rods of 

 B. termo lengthened into filaments, and that the spores formed in them 

 when set free germinated into short rods, I next directed my attention 

 to Micrococcus, in order, if possible, to make out whether it was a distinct 

 organism, or whether it was simply a phase in the life-history of some 

 common Bacterium, e.g., Bacterium termo. After making numerous 

 preparations, I at last succeeded in getting a cultivation in which only 

 Micrococci were present. The cultivation was made by adding to a 

 drop of humor aqueus from a fresh ox's eye a minimal quantity of pus 

 from a newly opened abscess on the point of a calcined needle. For 

 three days there was no indication of organisms, but on the fourth, 

 small moving particles were visible, which, when examined with a 

 No. XII immersion (Hartnack), were seen to be either round, oval, or 

 dumbbell-shaped, and often in groups of two and four. (Series YI, g.) 



A long and careful study proved that the diff erent forms were all' 

 phases of the same organism ; the oval forms became dumbbell-shaped, 

 and then divided into two round bodies similar to, but smaller than, the 

 sporules of Bacillus anthracis. The two round bodies moved actively 

 about till they separated from each other, when each became dumbbell- 

 shaped and divided as before. Being apparently in a suitable medium 

 and at a favourable temperature, they were extremely active and 

 increased so rapidly that they soon formed a large milky spot in the 

 centre of the cultivation liquid. This cloud, when examined with a 

 low power, was seen to dip well down into the fluid, thus correspond- 

 ing to the plug of Bacteria found by Professor Tyndall in several of 

 his test-tubes.* 



Though kept under observation for three weeks, not one of the 

 round or oval organisms present ever germinated into a rod. During 

 the fourth week three fresh drops of humor aqueus were infected with 

 the smallest possible number of Micrococci from the above preparation ; 

 also several flasks containing a sterilized turnip infusion, Both in the 

 aqueous humour preparations and in the turnip infusion they rapidly 

 increased, but none of them germinated into rods. This experiment 

 was again repeated with a like result. Hence, having failed to find 

 Micrococcus developing into Bacterial rods, it may, in the meantime, 

 be inferred that it is a distinct form : or just as Torula may be an 

 arrested phase of some Peuicillium-like organism, so may Micrococcus 

 be the spore of a Bacterium which has either altogether lost its 

 power to germinate, or can only do so under very peculiar conditions. 

 That Micrococcus closely resembles Torula will be at once apparent. 



* " Phil. Trans.," 1877. 



