1917] CURRENT LITERATURE 525 
tion of material which may aid in an explanation of the cause of these condi- 
tions. Unfortunately the experiments are limited and the analyses of the 
nitrogenous compounds are not sufficiently complete to furnish any sort of 
basis for judging what réle they may play. The data on the carbohydrates, 
however, are of considerable interest. In studying the effects of girdling on 
nutrition in general, at least three of the many points concerned in growth must 
be considered: (1) a possible modification of the intake of nutrients by the 
roots; (2) the synthesis of products from these compounds and those resulting 
from photosynthetic activity; and (3) whether these compounds are stored 
or utilized. We are given some light on the third point only. It is a fair 
question to ask whether the ability of the roots to take up salts is not as pro- 
foundly modified by the character and quantity of the organic nutrients in the 
parts above ground and with which such salts may be combined, as it is by the 
so-called starvation effects brought about by cutting off the supply of organic 
nutrients from the tops to the roots. Girdling could pring about _ en cet 
Situations. The question arises as to why the 
the girdles. As commonly stated, this may be due to the fact that these 
products are held from passing into the roots. There is little evidence which 
would show that it may not also be due to a deficiency of mineral nutrients, 
particularly nitrates, to aid in their utilization in forming other compounds 
or growth. study of the ratios of carbohydrates to moisture, nitrogenous . 
compounds, and other mineral nutrients in their relation to the entire phe- 
nomenon of growth is greatly to be desired. While this situation is not 
dealt with by Hrsrno, his results and those of several previous investigators 
furnish ample encouragement to warrant investigation. 
The increase in anthocyanin accompanying an increase in reducing sugar 
confirms the findings of previous workers with other plants. The yellowing 
of the foliage above a girdle is a usual condition. That this should accom- 
pany an increase in carbohydrates is interesting. It is unfortunate that no 
analyses of the nitrogenous compounds in the leaves are available. Lacking 
such determinations nothing can be said concerning their possible relationship 
to the carbohydrate situation, nor the moisture situation. The fact that the 
percentage of moisture in the leaves is lower when carbohydrates form a higher 
percentage of the weight might be expected when the moisture holding capacity 
of these compounds is considered. 
The single quantitative determination of the reserve materials in the twigs 
in midwinter is not sufficient for any general conclusions. Again, it is unfor- 
tunate that all the nitrogen is computed as protein. It is more than likely that 
all of it is not, and quite probable that the several forms of nitrogen may exist 
in different proportions in the several lots examined. A quantitative analysis 
at the time of active vegetation would have been even more significant regard- 
ing the influence of the several substances on growth. Striking as are the 
differences in the several lots, the results cannot be interpreted with certainty 
unless compared with figures for similar parts at several periods during the 
