On Certain Bacteria from the Air of New York City. 32^ 



the first five from surface colonies, the last five from deep ones, 

 and these were all planted at the same time on media exactly 

 alike, and grown on the same shelf under conditions as nearly 

 alike as possible. The following tables exhibit their relative rate 

 of growth. Number 7 failed to grow, probablj^ because no bacilli 

 were actually transferred from the colony, it being a "deep" one. 



,ai(The distauce of the line to the right in each column indicates the compar- 

 ative amount of action each culture had prodiiced. For example, in first table 

 on seventh day. No. 2 was farthest advanced and No. 6 least. ) 



Lactose-litmus Gelatin. 



Milk .21 cc. Acid.* 



*Each cc. required .21 cc. tenth normal NaOH to render neutral to phenol- 

 ptalein. 

 t Not planted at the same time as the others. 



