1915] CURRENT LITERATURE 501 
eas. The author emphasizes the fact that in the dwarf Hibiscus, as well as in 
dwarfs of other plants, numerous characters besides stature are modified, 
and expresses doubt concerning the possibility of interpreting such phenomena 
as due to a change in a single hereditary unit. The reviewer is inclined to 
suggest that, until there are available adequate data derived from crosses 
between the new and the normal types, little is to be gained by the assumption 
of either single or plural genetic changes, or indeed by a discussion of any other 
hypothesis.—R. A. EMERSON. 
Growth of sugar cane.—KvuYPER’ has investigated the growth of the leaf 
blade, leaf sheath, and stalk of sugar cane. His method was to make some 
holes (with a darning needle) through the young leaves and internodes. The 
distance between holes was made as uniform as possible; in practice the spacing 
could not be much less than a centimeter. After several days the leaves were 
removed, one after the other, and the distance between the holes measured. 
By comparing these measurements, the rate of growth of an area on different 
parts of the leaf, and ‘on different leaves, can be determined. The results 
indicated that the region of most rapid growth moves basipetally over the 
‘blade, then over the sheath, and finally over the internode. The region near 
the base continues its growth after the regions above have completed their 
development. These conclusions were confirmed by measurements obtained 
from equally spaced lines of India ink, and also by cell measurements. Regard- 
ing an internode bearing a leaf at its summit as the unit of structure, it may 
be said that the blade first becomes fully grown, then the sheath follows, and 
finally the internode develops. KuypEr shows how these conclusions may be 
applied in studying the “top rot” disease of Java. The cause of the disease 
must be sought in temporary unfavorable conditions of growth, and this inves- 
tigation furnishes a method of recognizing the period of growth influenced by 
these conditions.—J. M. C. 
Stomata of sugar cane.—KvyPER™ in connection with an investigation of 
the transpiration of sugar cane discovered a lack of knowledge of the structure 
of the stomata. Several methods were tried for measuring the width of the 
stomatal cleft. Direct measurements with the microscope proved impossible, 
not only because it is very difficult to make good preparations of the leaf for 
this purpose, but also because the variations in the opening are very small. 
Since, however, the application of the infiltration method of Miss E. Stern 
showed that great variations really exist in the rapidity with which paraffin 
and kerosene penetrate the leaf tissue, it was clear that there must be some- 
thing in the structure of the stoma which could explain this variation. The 
‘R, J., De groei van bladschyf, bladscheede, en stengel van het suikerriet. 
Ahi on voor ig Suikerindustrie in Nederlandsch Indié 23:528-540. pls. 2. 1915. 
.. De bouw der huifmondjes van het suikerriet. Archief voor de 
since ae in Nederlandsch Indié 22:1679-1707. figs. 6. 1914. 
