772 Transactions of the Society . 



are more circular — less elongated — than those of either of the other 

 organisms ; they stain, too, readily with the usual dyes, which the 

 others do not ; and thus the microbe may generally be distinguished 

 at a glance from either of its prototypes. 



Cultivated in nutrient gelatin it liquefies the medium regularly 

 from the point or line of inoculation, forming clouds or flecks in it, 

 but no pellicle ; in aga-aga bouillon or pepton it forms a creamy- 

 white scum on the surface, but does not liquefy the jelly. 



It might have been supposed that an organism, the habitat of 

 which is on the confines of perpetual snow, would have been more 

 at home at a low temperature ; it, however, developes more readily 

 at about 100° F. than at 50^ or 60°, though the diflference pro- 

 duces no appreciable variation in its form or habit. 



It does not develop in hay infusion, neutral or alkaline, this 

 character again at once distinguishing it from both the microbes 

 which it resembles in form ; neither does it germinate in solutions 

 of mineral salts. It will not develop in cultivating fluids that are 

 slightly acid ; • 1 per cent, of free hydrochloric acid in solutions of 

 pepton, or bouillon and pepton, entirely prevents its germination. 



It is not pathogenic when inoculated or injected in considerable 

 quantities into the tissues of rodents, and must be considered a 

 septic organism; it occasions, however, no very marked fetor in 

 the fluids in which it developes. 



It bears a general resemblance to the widely diffused bacilli 

 that occur so generally in putrid matter. The characters of these, 

 which' are probably of many different species and varieties, have 

 never been particularly described. They are sometimes termed 

 blood bacilli, from their occurrence in putrid blood, but have been 

 more appropriately named collectively by Klein * Bacillus septicus. 

 They, however, usually, or as far as 1 have yet observed, invariably, 

 form a pellicle in cultivating fluids, which the Niesen bacillus does 

 not. 



The labour and diflS.culty of such observations as those here 

 referred to, in which the microbe now described was obtained, is 

 obvious, involving the transport of the requisite apparatus and instru- 

 ments to such inaccessible places, and the obstacles to be overcome 

 in making experiments with the requisite precautions in these 

 situations. This, however, does not apply to the examination of 

 air at more moderate and accessible elevations, such for instance as 

 the hills and mountains of our own country, or even on high 

 buildings, where, as far as I know, no observations whatever have 

 as yet been recorded, though one of our own countrymen, as is 

 well known, has examined the air of the Alps, 



As an instance of how even comparatively slight elevations 



* 'Micro-organisms and Disease,' 1884, p. 78. 



