264 BOTANICAL GAZETTE [ocroBER 
while the tissue is practically neutral in February and March. He states also 
that there is a general correlation between acidity of tissues and the relative 
activity of diastase and maltase as determined from amount of glucose and 
maltose in tissues. _Maltose i is most abundant when acidity is high and near 
s 
the optimum for maltase activity. An average of eight determinations of 
maltose made in November, when acidity is highest, is 1.99 per cent, and an 
average of eight similar determinations made in March, when tissues are practi- 
cally neutral, shows 1.86 per cent maltose. This difference seems too insignifi- 
cant to conclude that maltose is present in larger quantities at a time when 
acidity is highest, especially when maltose determinations vary from 0.46 to 
3 or 4 per cent. e only conclusion concerning this, in the reviewer’s judg- 
ment, is that maltose is always present and in very variable amounts.—JOHN 
M. ARTHUR 
Ecology of the Gangetic plain.—In a paper of more than usual interest, 
DupceEon’ has included bbe results of his studies of a region whose ecology 
has been almost unkno This part of India, lying immediately about 
Allahabad, has a deceit whetodic: climate, with about 90 cm. of rainfall, and 
three distinct seasons. The rainy season, from June to the end of September, 
has high precipitation, high humidity, high temperature, and low insolation; 
the cold season, from October to the end of February, has high humidity, high. 
insolation, but low rainfall and low temperature ee 35° F. to ss’ F.); the 
third or hot season, has Jow rainfall and humidity, but high insolation and 
temperature (mean 80° F.). 
The existing vegetation is shown to be influenced quite as much by the 
biotic factors of a human population of 530 persons and 470 domestic grazing 
animals per square mile as by the nature of the climate. Most of the area is 
covered with dry meadow and thorn scrub, but it seems certain that these 
associations, now balanced against intense human influence, are really the 
retrogressive remains of a much richer climatic vegetation. The author seems 
to have thoroughly established his final conclusion, that “if the retrogressive 
influence of the biotic (human) factors were removed, the vegetation would 
pass through the progressively higher forest stages of (1) fully developed thorn 
scrub, (2) pioneer monsoon deciduous forest, and (3) climatic climax monsoon 
deciduous forest, a forest of considerable density and luxuriance.’’ This forest, 
as shown by adjacent regions, would show Terminalia tomentosa and Tectona 
grandis as dominant, and would also contain Sterculia spp., Bombax 
baricum, Anogeissus latifolia, Buchanania latifolia, Eugenia Janttolons, and 
probably Acacia catchu and Shorea robusta. —Gro. D . Fu ‘ 
6 DupGEON, WINFIELD, A contribution to the ecology of the upper Gangetic 
plain. Jour. "Ind: Bot. 1:1~29. figs. 9. 1920. 
