1917] CURRENT LITERATURE 343 
Mottling in citrus leaves.—JENSEN™ has attempted to see whether there 
is any relation between mottling of Citrus leaves and the supply of nutrient 
salts necessary for chlorophyll formation. Such was thought possible since 
the Office of Biophysical Investigations had found that mottling is inversely 
proportional to the humus content of the soil, and that decomposing organic 
matter increases the soluble salts in the soil:of the groves. The following 
statements from h 'y indicate t Its of the investigation: ‘Judged 
by a comparison of the average percentages of the inorganic elements deter- 
mined in healthy Citrus leaves and in leaves in the medium stages of mottling, 
the data obtained did not show that the initial mottling could be accounted for 
by deficiency in the transfer of the iron, calcium, magnesium, and phosphoric 
acid from the conducting system of the leaf stem and midrib to the mesophyll 
tissue. On the other hand, sharply localized yellow areas in old orange 
leaves contained less of these elements than the adjoining green areas (mostly 
veins), but whether that relation obtained in the initial stage of mottling was 
not determined. In very badly mottled Citrus leaves there was in general 
an increase in the percentage of these elements in the conducting tissues, includ- 
ing the leaf stems, indicating difficulty in their transfer to the inesophyil tissues 
in very —— stages of mottling, probably because the leaf had become 
functionless. 
‘The process of mottling is seemingly very complex, involving as it likely 
does an unusually rapid decomposition of chlorophyll and not merely a cessa- 
tion in chlorophyll formation. This problem may yield to solution, if at all, 
only after a many-sided attack. In some of the algae, however, loss of chloro- 
phyil seems to be a direct result of shortage of nitrate supply. Work of this 
this as a possibility in Citrus plants, as well as to indicate 
the complex nature : of the process. —Wwm. CROCKER. 
Monocotyledony.—WorsDELL® has criticized the reviewer’s view of mono- 
cotyledony in a paper which “‘is an astonishing one.” In fact, we seem to be 
mutually astonished, neither being able to understand the reasoning of the 
other. The paper opens with an account of “an uncommon abnormality,” 
which consists of a ‘forked coleoptile”’ in a corn seedling, and this phenomenon 
is the excuse for the rest of the paper. It may be well to record that this 
“forked coleoptile” is a very common phenomenon, as all know who have had 
much to do with corn ‘Seedlings 1 ” nets eeitivarios. 
The author h f zonation , which are 
fundamental in this connection, and zonation is by no means a “s 
phenomenon.” Zonation enables one to realize, for example, that a prominent, 
# Jensen, C. A., Composition of Citrus leaves at various stages of mottling. 
Jour. Agric. Research 9:157-166. 1917. 
%3 WorspELL, W. C., The morphology of the monocotyledonous embryo and of 
that of the grass in particular. Ann. Botany 30:509-524. figs. 10. 1916. 
