April, 1910.] 
The Bacterial Flora. 
*45 
and unproductiveness of soils. If attempted, the interpretation 
would be indeed, one-sided; there is a co-ordination of factors, 
each and all of which exert a relatively marked influence. Cli- 
matic conditions, temperature, water, and air conditions in the 
soil, as well as the phsvcial and chemical character of it, and the 
surface flora, all play an important role in determining the 
character of a vegetation and of its bacterial flora, and therefore 
also the character of the chemical products formed. 
One should constantly keep in mind the genetic idea in the 
study of edaphic, climatic, or biotic investigations. Soil, 
climate and flora are the product of the conditions of their 
Fig. 2. Wheat plants growing in i per cent, peptone bog-water solutions 
inoculated with pure cultures of bog bacteria. Numbers correspond with 
data in Table III. 
development; their peculiarities are closely interrelated in the 
dynamics of the process. Wherever the same factors are pres- 
ent, the results will be similar. The bacteriological-chemical, as 
well as the physiological method, deserve on that account a 
closer consideration. The determination of the bacterial trans- 
formation products and the more detailed study of their phvsio- 
logical properties should possess an exactness and a reliability 
to make them suitable for the solution not onlv of agricultural but 
of ecological problems as well. It is only too clear that the need 
for new investigations in this phase of the problem is pressing, 
and that especially new points of view and new lines of research 
are imperatively required. 
Botanical Laboratory, Ohio State University. 
