478 



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



of B. anthracis are destroyed when the fluid they are suspended in is 

 kept for a few minutes at the point of ebullition. The same is true of 

 B. termo and Micrococcus. On the other hand, when they are sub- 

 jected to a temperature of 110° C. in a dry state they are not destroyed ; 

 they are rendered inactive, however, by a temperature of 120 s C. The 

 difference between the effects of moist and dry heat is probably owing 

 to the gelatinous capsules of the spores and Micrococci giving way, 

 and thus allowing the boiling fluid to come into direct contact with 

 the unprotected central protoplasm. 



Further Observations on Bacillus. 



On the surface of sea water, containing the remains of seaweeds, 

 Pedicellinge and skeleton shrimps, brought from Roscolf by Mr. Greddes 

 last April, a few patches of scum appeared which, on examination, 

 were found to be made up of active and resting Bacilli, exactly 

 resembling in size and form Bacillus subtilis. Day by day the small 

 pellucid areas increased until the whole surface of the water (about 12 

 centimetres in diameter) was completely covered with a thick opaque 

 scum, which, after remaining entire for seven days, gave way in the 

 middle, and soon sank to the bottom, remaining there in a torn and 

 broken condition. 



The minute spots which first appeared were almost entirely made 

 up of active Bacilli, rapidly multiplying by transverse fission. As the 

 patches increased in size, the Bacilli either formed zoogloea, or length- 

 ened into filaments. The process of lengthening was, as compared 

 with B. anthracis, when cultivated on the warm stage, a remarkably slow 

 one, and often the filaments which with the No. VIII Hartnack were 

 apparently 3 or 4 centimetres in length, moved in a languid way amongst 

 the active Bacilli. Having increased to about forty times the length 

 of the original rod, the protoplasm divided and condensed into spores, 

 the steps of the process being similar to those already described in B. 

 antliracis* The spores next escaped from the filaments, and either 

 formed zoogloea, or germinated into another generation of rods. This 

 increase of the rods by simple division, and by spore formation, con- 

 tinued until the whole of the surface of the water was covered by the 

 scum. 



On examination, six days after the scum sank to the bottom, an im- 

 mense zoogloea was found made up of a relatively small number of 

 quiescent rods, embedded in a thick transparent matrix (Series I, j). 

 But of especial interest were a considerable number of large and small 

 granular masses, made up of minute round particles, the smaller ones 

 resembling the "cell families" of Ascococcus,\ and the larger ones 



* Loc cit. 



f Colm, " Beit, zur Biol, der Pflanzen." 



