778 SUMIV-R"^' OF CURRENT RESEARCHES RELATING TO 



striking in wet or cold localities, he attributed to the excessive 

 humidity of the preceding summer. No organs of reproduction were 

 observed. 



Bacteria living- at High Temperatures.* — Cohn has assigned 

 55° C. as the highest limit of temperature at which the Bacteria he 

 studied, and notably Bacilli, still lived and developed. This 

 temperature is, in fact, M. P. van Tieghem says, fatal to most of 

 these organisms. Nevertheless he last summer observed several 

 which developed rapidly and formed their spores regularly, at the 

 considerably higher temperatures of 60°, 65^, 70°, and up to 74°. In 

 a d'Arsouval apparatus, regulated at fhe latter temperature, several 

 successive growths of two of the organisms were obtained. 



One was a Micrococcus whose spherical cells were arranged in 

 long chaplets, the " beads " measuring 0-0015 mm. They developed 

 throughout the nutritive fluid, which they rendered uniformly turbid. 

 The other was a Bacillus with very pale joints, always stationary, 

 spreading over the surface in a thin mucous pellicle. Its cells disunited 

 immediately after their division and placed themselves parallel to 

 each other, thus forming long palisade-like series in which the 

 " battens " were bound together by a gelatinous substance. They 

 formed their spores rapidly and disappeared, leaving those spores 

 arranged side by side in transverse series as they themselves had 

 been. 



In these cultures an infusion of kidney-beans or broad-beans 

 filtered and perfectly neutralized was the nutritive fluid employed. 

 It was first heated in the stove to 74°, and the sowing made on the 

 spot. Thus the objection cannot be raised that the development 

 observed could, at least in part, have taken j^lace during the time 

 consumed in heating the liquid. It is also necessary that the latter 

 should be and remain neutral. Should it be slightly acid all 

 development will soon cease. This explains the fact that, under these 

 conditions, the development of the two organisms only took place 

 during the first two or three days after the sowing ; later on the fluid 

 again became clear, and thenceforth sterile. A certain amount of 

 acidity produced by the organism itself is then always observable, 

 which soon renders the fluid uninhabitable by it. Moreover, the 

 Bacillus quickly produced its spores, which were set at liberty after 

 the end of the second day. 



At the temperature of 77° the development of the Bacillus no 

 longer took place, and fluids sown with its spores preserved their 

 clearness. 



In conclusion, M. P. van Tieghem mentions that he is induced to 

 publish these observations by the remarks of M. P. Miquel | of the 

 existence in ordinary water, especially that of the Seine, of an 

 immobile and filamentous Bacillus that " readily supported a tempera- 

 ture of 60° to 70°," and, cultivated in a neutralized meat infusion at 

 69° to 70°, " produced filaments, pellicles, and spores, the luxuriance 



* Bull. Soc. Bot. de France, xsviii. (1881) pp. 35-6. 



t ' Annuaire de 1 01)servatoire de Moutsouris pour 1881 (Meteorologie),' p. 4G4. 



