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CURRENT LITERATURE 229 
such useful and unfamiliar facts as the time of seeding, the treatment of 
forest tree seeds, the management of the forest nursery, planting, pruning, 
forest management, etc. With these, which are evidently based on experi- 
ence, are full descriptions of the trees of Minnesota. It will prove valuable 
far beyond the limits of Minnesota. — CHARLES A. KEFFER. 
THE work of Rimbach on geophilous plants has been previously alluded 
1 He has recently published a contribution on the growth of rhizomes in 
depth* Rhizomes have a so-called normal depth, varying with the species. 
Rimbach’s experiments show that a removal of the soil from over a rhizome 
causes a downward growth, while a deep burial causes upward growth. 
These results are commonly brought about by a change in the direction of the 
thizome axis, though sometimes by root contraction. Since these changes 
donot take place until some organ of the plant reaches the surface, the 
author thinks that they are caused by a greater or less need for structural 
materials on the part of the plant. H. C. Cow Les. : 
val ay makes a preliminary announcement of a forthcoming paper 
xperimental work on autumnal coloration. This much-vexed sub- 
< long needed careful physiological investigation. He thinks that the 
eh ers of plants are probably glucosides, and in most cases 
are sunshine saat with sugar. The chief physical factors involved 
prevents ed ich augments sugar production, and low temperature, which 
Sugar in auty “ieciaiiad of sugar into starch. The replacement of starch a 
Overton ae ae <teieal leaves had previously been shown by Lidforss. 
v feed : . ted tints could be produced in many leaves at any season 
ing them with glucose. — H. C. CowLes. 
.G 
tact alg BITTER” has made some extended observations on the con- 
pn oP of growing crustose and foliose lichens. The relationship is 
a Saprophytic nature. In some instances contact lines 
ena a eats 
View is ss oy the nature of parasitism (antagonistic symbiosis). The 
se i ; , 
the substratum that lichens take but comparatively little nourishment from 
vs 96. Jan. 1899, 
a 68: 33-44. 1896, 
' 
Jahrb £, wiss Spates der Krustenflechten beim Zusammentreffen ihrer Rander. 
"333 47-127. figs. 7-14. 1898, 
