CURRENT. LITERATURE 
BOOK REVIEWS 
Transpiration of plants 
BURGERSTEIN’s' second volume on the transpiration of plants constitutes 
a supplement to his well known work published in 1904. It presents a critical 
summary of the literature on transpiration down to and including the year 
1920. The first volume was based on 394 publications, while in the second 
volume 505 have been added, many of which were published in English, and 
an unusually large number by women. The first volume contained 30 chapters, 
the second 32. They parallel each other very closely, but a comparison of 
the two brings out rather clearly the more recent trend of this line of investiga- 
tion. Many of the subjects mentioned in the text in the first volume are here 
given separate chapter treatment. Thus the principal advances made in the 
study of the transpiration of plants during the last sixteen years are clearly 
indicated. A number of new terms and phrases appear in the second volume 
which were not used in the first, and most of which are concerned with an 
attempt on the part of the investigator to obtain a more satisfactory basis for 
the comparison of the amount of ermueenas of different plants at different 
times and under different conditio 
Relative transpiration is the Bane of transpiration of any plant at any time 
to the water loss from a standardized water surface, or from any other water- 
evaporating surface exposed under the same conditions as is the plant, and for 
the same length of time. In most of the papers in which this term is used the 
assumption has been made that evaporation is a correct measure of the environ- 
mental conditions affecting transpiration, and that therefore any variation 
which occurs in the plotted graph showing ratio of transpiration to water 
loss is due to some adjustment on the part of the plant. This assumption is 
made without sufficient reason and is not well supported by experimental data. 
Index of transpiring power differs from relative transpiration only in that 
a cobalt paper is introduced as an indicator of relative water loss; consequently 
any errors inherent to the relative transpiration method are not eliminated by 
this method, and there is also introduced the uncertainty connected with the 
use of the cobalt paper. Both of these methods have been used extensively 
and have stimulated an unusually large amount of investigation. While the 
accuracy of the results must be questioned, it is undoubtedly true that our 
knowledge of transpiration has been greatly advanced by their application. 
* BERGERSTEIN, ALFRED, Die Transpiration der Pflanzen. Zweiter Teil (Ergin- 
zungsband). Jena. 1920 
239 
