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1906] CURRENT LITERATURE 363 
His objects were (1) to compare the winter transpiration of these species in Rome 
with that already observed by Kusano in Tokio during the winter; and (2) to 
compare the winter and summer transpiration in Rome. One set of experiments 
was made with single leaves exposed 24 hours in GARREAU’S apparatus, and 
another series with small twigs (in one case a leaf only) attached to MoLt poto- 
meters. The potometer measurements were usually continued for about 8 days 
and readings made at 9 A. M. and 5 P. M. 
The author found the winter rate of transpiration at Rome decidedly greater 
than that at Tokio. He obtained for an average value of the ratio of winter to 
summer transpiration at Rome, for all the species examined, 1:3.10. The aver- 
age ratio at Tokio of Kusano’s “typical plants” (species not given) was 1:20, 
PUGLISI reports that transpiration continued at night during the minimum 
temperature of his experiments, 2.6°. The rate of transpiration continued to 
increase with the rise of temperature up to and including the hottest days of 
July in which experiments were made 
There is a notable difference among the plants experimented upon in the 
sensitiveness to change of temperature. Measured by GARREAU’s method, 
Ficus erecta showed an increase of 1.5 times in the amount of transpiration when 
the temperature rose from 6.4° to 21.6°, and Raphiolepis japonica showed an 
increase of 7 times for about a degree more of rise than that of the Ficus. 
The paper contains many interesting data, but the author has not sufficiently 
REAU method. All of the winter measurements were made by this method, 
which eliminates the effect of changes in relative humidity at a season when the 
actual range of this factor was from 58 to 95 per cent.—J. Y. BERGEN. 
Plant breeding in the tropics —Locx" gives a further account of his studies 
in plant breeding at Peradeniya, Ceylon. His general conclusions were given 
in an earlier paper, and the present contribution describes in detail the experi- 
ments with the genus Pisum. Records of climatic conditions are given, and 
the changes which were induced in various European varieties on introduction 
into Ceylon. There was no gradual adjustment or acclimatization, the change 
of stature, habit, etc., being immediate and permanent during the several years 
of the investigations. 
In all of the experiments wherein the characters are clearly alternate, the 
agreement with theoretical ratios is as close as the numbers used would warrant 
one to expect, on the hypothesis that the union of gametes bearing the several 
characters is purely a matter of chance. The author greatly weakens his paper, 
however, by pointing out Mendelian ratios where they are wholly unwarranted by 
his data, as for instance in width of pod (p. 371), where a variation curve with 
"8 Lock, R. H., Studies in plant breeding in the tropics. Ann. Roy. Bot. Gardens 
Peradeniya 2: 357-414. 1905. 
