Bacterial Flora of the Semi -Desert Region of New Nexico. 217 



difference is even greater when different periods of time are 

 taken. Perhaps an average of the three plates taken gives 

 us a figure that is fairly representative. 



Exp. 8. — December 7, 1898. Three agar plates were 

 exposed about 30 rods east of buildings for 30 minutes. Air 

 was clear and cold, with slight breeze from the south. 

 December 12. — No growth. P]ates were kept too cold. 

 December 22 : 



PI. 1. — 75 bacteria (6 spp.) and 7 molds, 

 PI. 2. — 113 bacteria and 4 molds. 

 PI. 3. — 260 bacteria and 10 molds. 

 Average per 10 min., 49.8 bacteria. 

 Again note the variations in numbers. A 5 and Am were 

 isolated from above plates. 



Exp. 9. — December 20, 1898. Three agar plates were 

 exposed simultaneously as follows : 



No. 1. — 15 min. in Biological Laboratory on table. 

 No. 2. — 15 min. in open air north of building. 

 No. 3. — 15 min. in private residence near by. 

 January 1, 1899 : 



No. 1. — 36 bacteria and 1 mold. 

 No. 2. — 92 bacteria and 3 molds. 

 No. 3. — 106 bacteria and 6 molds. 

 Average per 10 min. (No. 2), 61.3 bacteria. 

 These results are interesting, since they give us a com- 

 parative idea of the number of bacteria found in rooms as 

 compared with open air. More bacteria were expected from 

 the Laboratory. 



Exp. 10. — December 31,1898. Exposed four plates 30 

 rods east of main building for 30 minutes. Clear and cold 

 with stiff breeze from northwest. 

 January 13 : 



No. 1 (glucose gelatin). — Spoiled by large numbers of 

 molds which luxuriate on sugar media. 



No. 2 (gelatin). — 15 bacteria and 5 molds. Colors of 

 colonies are not well defined on this medium. 



No. 3 (agar). — 57 bacteria and 2 molds. 



No. 4 (agar). — 123 bacteria and 9 molds. 



Average per 10 min., 21.6 bacteria. 



7 



