236 



Cincinnati Society of Natural History. 



As to the source of these organisms, nothing is positively 

 known. Analysis of superficial layers of the soil show their 

 presence, but this might be attributed to their falling upon 

 the ground. At a depth of several inches we find an entirely 

 different flora, which comprises mostly non-chromogenic, 

 spore-bearing, liquefying bacilli. These have never been 

 worked out in detail. The waters from the Rio Grande do 

 not contain our air flora to any material extent. Analysis of 

 milk from a number of dairymen show different results. At 

 times they are quite absent, and this is especially true of the 

 more careful and cleanly dairies. At other times they form a 

 large proportion of the milk flora. In these instances it is 

 believed, however, that they invariably gain entrance from 

 the air through carelessness on the part of the dairyman. It 

 would appear most probable then that our flora is obtained 

 from the superficial soil layers, especially in moist places. 



It has been mentioned that many of the air bacteria may be 

 isolated from milk. It may not be inappropriate to record 

 here, the fact that the typical milk flora, as found else- 

 where, is also characteristic here. B. acidi lactici j(Hiippe) 

 and B. lactis acidi (Marpman) have been found in all samples 

 analyzed, and coming from a number of dairymen who deliver 

 milk in the city of Albuquerque. 



It may also be mentioned that search has been made for 

 B. tetanus in garden and other earth, through animal inocula- 

 tion, but it has not as yet been found. 



Search has been made for B. subtilis on native hay, but 

 repeated cultures in bouillon have failed to reveal it. B. 

 mesentericus vulgatus can be regularly obtained from native- 

 grown potatoes. 



Descriptions of Air Bacteria. 



Of the fourteen organisms isolated, nearly all were present 

 on the plates a number of times. These have been quite fully 

 described during the work; the characteristics being corrob- 

 orated by one or more subsequent cultures. It has been 

 thought worth while to include ten of these descriptions in 

 this place. They are as follows: 



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