294 
F. C. NEWCOMBE AND ETTA A. BOWERMAN 
The chambers for securing stagnant air have varied in size from 
bell jars of about 6 liters capacity to darkrooms of 12 cubic meters. 
While one set of plants was growing in the chambers in quiet air, 
another control set was always growing in a chamber of equal or 
larger size whose air was stirred constantly with a fan or with a blower. 
The criteria for comparing behavior in ciuiet and moving air were 
duration of vital period in the dark, size of seedlings, size and number 
of leaves formed, general vigor of the plants, phenomena of geotropic 
and heliotropic reaction. 
It may be said in a word that no ill effects manifested themselves 
as due to confining plants in stagnant air in small or in large chambers. 
The greatest objection to small chambers, as bell jars, comes from the 
growth of injurious fungi on the plants, due to the excessive moisture. 
This ill effect mostly disappears when the plants are kept in a larger 
chamber, or when care is taken to keep the uppermost stratum of 
the soil free from excessive moisture. 
With but few exceptional cases, the cultures have shown that in 
small chambers, like bell jars, seedlings grow taller, produce larger 
and more numerous leaves, and become exhausted so that they fall 
over a day or two earlier (at 20°) than in a larger ventilated chamber. 
These differences were pronounced when comparing plants grown 
under bell jars with similar plants grown in moving air, the moving 
air coming either from the outside or being circulated within the dark- 
room. The differences were much less when the chamber with stag- 
nant air was increased to a fifth of a cubic meter, and disappeared in 
most cases when the two chambers for comparison were 12 cubic meters 
each, the one with stagnant, the other with circulating air. 
This larger and more rapid growth in very moist air is no new dis- 
covery. It has been cited by Wiesner^ and by Eberhardt."^ 
Not only is ventilation of no effect in producing better seedlings in 
a small or large chamber in the dark, but it has no visible effect on 
the sensitive reactions of geotropism and heliotropism. 
Botanical Laboratory, 
University of Michigan. 
^ Wiesner. Formanderungen von Pflanzen bei Cultur im absolut feuchten 
Raume und im Dunkeln. Ber, Deutsch. Bot. Ges. 9: 46. 1891. 
* Eberhardt. Action de I'air humide sur les vegetaux. Compt. Rend. Acad. 
Sci. (Paris) 131: 193. 1900. 
