158 BOTANICAL GAZETTE [FEBRUARY 
the results of cultures of 1909, marking the beginning of the second decade 
of the work. In the season covered by the report, 15 species of rusts were 
each sown on a large number of aecidial hosts with negative results. Sowings 
of 23 species were made supplementing or confirming previous work of the 
author and others. Of special interest among these is the sowing of Calyp- 
tospora columnaris on potted plants of Abies Fraseri. The successful culture 
of the aecidia on Abies led to the subsequent discovery of the native aecidial 
form on Abies balsamea in Nova Scotia, whence the original Calyptospora 
material had been obtained. This fe of the aecidia by Professor 
FRASER is the first from America. Of teleutospore forms connected for the 
first time with aecidial forms, 6 are reported. These are Puccinia Ceanothi 
(Ellis and Kellerm.) Arth. on Andropogon Hallii Hack. and Ceanothus ameri- 
canus L.; Gymn ene exiguum Kern on Juniperus virginiana L. and 
Cattanee Pringlei Sarg.; G. corniculans Kern on J. horizontalis Moench, 
Amelanchier erecta, and “ canadensis (L.) Medic.; and G. trachysorum Kern 
on J. virginiana L., Crataegus aise Jacq., C. coccinea L., and C. cerronis 
A. Nels.—H. HAsseLaEmc. 
Rate of photosynthesis.—THopavy* comes to the defense of the increased 
weight method of Sacus for determining the rate of carbon fixation in green 
plants. He thinks he has sngun out the details of the method so as to insure 
quantitative accuracy. One cannot see how it will lead to more accurate 
results than the method deseribed in GANONG’ . Plani physiology (2d ed., pp. 
about what occurs in a leaf subjected to illumination. As BRowN and EscoMBE 
suggest in stating their CO. intake method, it may modify the power of various 
contained compounds to hold water at 100°C. Since the amount of atmos- 
pheric CO, fixed is the question to be answered, the reliability of the increased 
weight method must be measured by its agreement with the amount of CO; 
taken up under like conditions. It would seem as though the work better be 
done on perfecting the CO, intake method, if indeed Brown and EscoMBE 
did not leave it so. This method is entirely independent of asymmetry, of 
variation of surface with insolation, and of translocation and changes in the 
water-holding powers of the leaf. It also measures directly the thing sought. 
THODAY depended upon the horn hygroscope as a means of determining the 
condition of stomata. The results obtained with this instrument are at 
best only indirect and qualitative, as Lioyp has suggested. The direct 
and accurate method devised by Lioyn is certainly preferable —WILLIAM 
CROCKER. 
3 THopay, D., Experimental researches on assimilation and respiration in the 
open air. Proc. Roy . Soc. London B 82:421-450. 1910. 
37 Ltoyp, F. E., Physiology of stomata. Publ. 82, Carnegie Institution. 1908. 
