218 



Cincinnati Society of Natural History. 



Exp. ii. — February 13, 1899. Four plates were exposed 

 20 rods north of main building, all for one hour. 



Conditions: Partly cloudy with slight breeze from south. 

 Moderately warm after cold wave. 

 February 25 : 



No. 1 (agar). — 21 bacteria and 3 molds. 

 No. 2 (agar). — 33 bacteria and 2 molds. 

 No. 3 (gelatin). — 27 bacteria and 8 molds. 

 No. 4 (gelatin). — 10 bacteria and 5 molds. 

 Average per 10 min., 3.8 bacteria. 

 Exp. 12. — March 28, 1899, 10.20 a. m. Exposed four plates 

 north of University grove for 30 min. 



Conditions: Clear; moderate breeze from southwest; 

 slight snow storm on 27th, which makes the ground wet 

 to-day. 

 April 7 : 



No. 1 (agar). — 10 bacteria and 4 molds. 



No. 2 (agar). — 9 bacteria and 3 molds. 



No. 3 (gelatin). — 18 bacteria and 4 molds. 



No. 4 (gelatin). — 20 bacteria and 2 molds. 



Average per 10 min., 4.75 bacteria. 

 It might appear from this experiment that the gelatin 

 medium developed more colonies than agar, but this does 

 not hold in other exposures, as in Exp. 11, for example. 



Exp. 13. — October 5, 1899, 3.45 p. m. Three agar plates 

 were exposed north of grove for 28, 40, and 60 min. respect- 

 ively. 



Atmosphere was clear and calm. 

 October 11 : 



PI. 28 min. — 51 bacteria (4 spp.) and 6 molds. 



PI. 40 min. — 290 bacteria (5 spp.) and 19 molds. 



PI. 60 min. — Covered with molds. No count made. 



Average per 10 min., 49 bacteria. 

 Spp. present : A,, A 2 , A3, A 4 , A 5 . 



Note. — Plates 20 and 40 minutes were photographed to 

 show the relative numbers of bacteria, as well as the size of 

 colonies, etc. See Figs. I and II, page 219. 



Exp. 14. — October 19, 1899, 3.18 p. m. Made three agar 

 plate exposures north of grove. 



Atmosphere clear, calm and warm. 



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