Tae Carson DtoxtpE OF THE Soru AIR 325 
Fic. 44. CANS USED IN FIRST EXPERIMENT 
The four cans at the left contain an oat crop, which is shown at the period of its growth a month before 
the maximum amount of carbon dioxide was found in the air of the cropped soil 
Fie. 45, ARRANGEMENT OF CYLINDER, SAMPLING FLASKS , AND ASPIRATOR 
