1905] CURRENT LITERATURE 227 
while the hazel is the chief shrub. The herbage is so dense as to exclude most 
mosses. The formation is often developed from salt marshes and HEssELMAN 
gives an interesting account of the developmental stages. The alder is commonly 
the pioneer ligneous form, and is followed by the ash. The author’s most impor- 
tant contribution is experimental, and in this field he has clearly pushed forward 
the frontiers of our knowledge. His results deal chiefly with the ecology of starch 
formation, respiration, and transpiration. An important feature of his results 
is that they are rigidly quantitative. In the study of starch formation, close 
correlation was made with the light intensity, in which WrESNER’s methods were 
employed. The “Lichtgenuss” varied from about 1 in open meadows to #5 in 
dense hazel thickets. Much formation of starch was observed under the trees in 
early spring, and all through the summer as well in open meadows. The very same 
species that were found rich in starch in the woods in spring were found nearly 
Without it in the summer shade. In the ash woods, however, starch is formed in 
summer by all herbs, except a few which are always poor in starch. This is corre- 
lated with the greater light intensity of ash woods, as compared with other kinds. 
Anatomical studies are also correlated with the above, and it is found that those 
plants which develop their leaves late in the forest shade have a weak develop- 
ment of palisade cells, while the plants which develop their leaves in the intenser 
light of early spring have more palisades. Trees with high light requirement 
were found to have but one leaf type, namely a sun leaf; while shade-enduring 
trees have both sun or shade leaves, depending on their growth conditions. Trees 
of the first class, such as the ash or birch, show starch formation in all leaves, 
wherever placed. Plants of the second type, such as oak or hazel, do not form 
Starch in the innermost leaves. In equal light shade leaves form more starch 
than do sun leaves of the same species. Starch formation decreases from spring 
to summer in the woods more in sun plants than in shade plants. Shade plants 
Tespire much less than do sun plants. Shade plants transpire much less in the 
shade than do sun plants in the sun, especially on hot or dry days. The leaf 
surface being equal, plants transpire more as they have a greater development 
of palisade cells, though many have thought that palisade cells in some way chec 
transpiration, since they commonly occur where such protection seems necessary. 
The great detail with which HessELMAN’s studies have been pursued, and 
the tedious quantitative experiments, may well furnish a model for many workers 
in all lands. The paper is illustrated by several reproductions of photographs, 
and a number of text figures showing anatomical details —H. C. Cow Les. 
_ THE AcHRoMATIC figure in Pellia epiphylla has been investigated again, this 
time by GREGorrE and BERGHS,™ who have devoted their attention to the intra- 
Sporal mitoses of the germinating spore, and in some degree to the first mitosis in 
the spore mother-cell. The figures show some improvement over those of their 
Predecessors and indicate a technique of the highest order. The researches of 
Senses 
*? GRrecorre,V., and BERGHS, J., La figure achromatique dans le Pellia epiphylla. 
La Cellule a1: 193-233. pls. I-2. 1904. 
