1915] CURRENT LITERATURE 503 
in the past, of considering a degree in one part of the temperature scale the 
equivalent of a degree at any other part of the scale, as is done in the use of the 
annual mean temperature or even in totaling the degrees of temperature for 
the growing season. Although more attention has been given to the tempera- 
ture phenomena of the growing season, he believes that the temperature phases 
of the frost season are perhaps of equal importance, especially in determining 
the distributional limits of some simian eats peas. He has already shown, 
as noted in this journal,?s that the temperat mountains is often 
complicated by cold air drainage, but it ere appear that in such situations 
i 
mperature is the factor most closely corresponding in its distribution with the 
che gate of the species concerne is would harmonize with SHREVE’s*® 
experiments with the giant cactus, ‘ich show that the number of hours of 
exposure to temperature below freezing determines its death, without regard 
(within certain limits) to the absolute minimum reached. Thus Cereus 
giganteus is unable to resist freezing of over 19-22 hours duration, while other 
related Arizona species withstood periods up to 66 hours, and Opuntia mis- 
souriensis has been known to survive 375 consecutive hours of freezing tem- 
perature in Montana. The importance is thus emphasized of applying the 
exact quantitative methods of physiological work to plant geography in order 
to place its generalizations upon a secure logical basis. 
In this connection it is interesting to note the method described by 
MctiouaTs of applying to the summation of temperature in hour-degree 
units for a given time a factor expressing the rate of growth of a particular 
species, in order to give the relative values of such temperature exposures.— 
EO. D, FULLER 
Production of alcohol by higher plants.—MINENKOw,* investigating the 
question of alcohol production by higher plants fully aerated, and the influence 
of osmotic pressure and temperature on the process, finds that well aerated, 
sterile solutions of glucose (15.8 per cent), sodium sulphate (6-7.8 per cent), 
and di-potassium hydrogen phosphate (7.25 per cent) retard germination of 
Vicia Faba and favor alcoholic production so that the ratio of carbon dioxide 
to alcohol approached nearer the value observed for alcoholic fermentation 
han with seeds germinating in water. Growth was retarded by these 
25 Bot. GAZ. §5:263. I1913- 
26 SHREVE, F., The influence of low temperature on the distribution of the giant 
cactus. site World 14:1360-146. Igrt. 
27 McDovaeat, D. T., The auxo-th ] integration of climati pl Amer. 
Jour. Bot. 1:186-193. 1914. 
28 MineNKow, A. R., Die alkoholische Girung hoéherer Pflanzen. Biochem. Zeit- 
schr. 66:467-485. 1914. : 
