64 BOTANICAL GAZETTE [juLY 
are cut in the same way and then placed on pedestals. When the 
whole active part of the seedling is under water growth ceases, but in 
moist air they do very well. Seeds kept some months in the very dry 
air of the laboratory refuse to germinate.—EDWIN BINGHAM COPELAND, 
Stanford University, California. 
CONTRIBUTIONS TO THE BIOLOGY OF RHIZOBIA. 
III. NOTES ON THE WINTER AND EARLY SPRING CONDITIONS OF 
RHIZOBIA AND ROOT TUBERCLES 
THE major observations here recorded were made during the winter 
and early spring of 1893 and 1894; incidental observations were also 
made during subsequent winter seasons. The object was to obtain 
more definite information regarding the permanency of leguminous 
root tubercles and the viability and natural resistance of rhizobia to 
low temperatures, more especially low temperatures with frequent 
changes to higher temperatures as in the winter months of the central 
states, Illinois in particular. Sudden changes of temperature, though 
not necessarily fatal to life, have a pernicious effect upon low organ- 
isms. The effects of temperature and other climatic conditions become 
gradually less with increase in depth of soil. The organisms found in 
the surface soil are most directly exposed to the pernicious climatic 
changes. 
From the following table of mean monthly averages for the months 
of November, December, January, February, and March, 1902~3, with 
a list of coldest days of each month, it will be seen that the variation 
in temperature was considerable. Very cold weather (— 10° to — 15° 
F.) did not continue for more than a few days at a time. 
Month Min. ° F, | Max. ° F. | Mean ° F. Coldest days ° F. 
November ........ 25.9 52.1 3703 6, 14, 16, 18, 18 
December ........ 19.9 38.4 30.0 | — 6, 3, 5, 4, 6 8, 9. 
January .......... 20.3 39.7 29.4 —21, Ba 2, 50, 
February ...2..... 15.6 33-9 24.7 |— 5, ce Sar "8. 
Marehiis,) ges 32.9 55-6 43-5 10, II, 12, 16, 24. 
The humidity during the months indicated was somewhat above 
the average for the state of Illinois. The ground was covered with 
snow during parts of the months of January, February and March. 
Soil covered by snow banks was not frozen at any time. The open 
unprotected soil was frozen to a depth of about eighteen inches during 
January, February and the early part of March. 
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