76 BOTANICAL GAZETTE [JANUARY 
has altered our notions cencerning the prevailing deep-rootedness of desert 
plants. In a recent short paper he brings further data along similar lines. 
The mesquite, as is well known, either may be a shrub or it may be a tree of con- 
siderable size. On flood plains, where it is a tree, its roots penetrate to the 
water table, whose depth may be 15-25 feet. Shrubby specimens on higher 
grounds have extensively spreading rather than deep roots. CANNON con- 
siders the root situation in different types of climate and makes several inter- 
esting suggestions. 
In a brief notes» CANNON calls attention to the somewhat curious fact that 
at Carmel, California, the removal of the chaparral undergrowth in forests 
of Pinus radiata is followed by the death of the pines. This is attributed to 
the shallow root system of the pines, which comes to grief when the soil is 
desiccated as a result of the removal of the chaparral—H. C. CowLes. 
Sand hill forestation—Some government experiments of considerable 
interest to ecologists are being conducted in the sand hills of Kansas and 
Nebraska, as noted by BaTEs and Prerce.# While the sand hills of Kansas 
are not extensive, almost a fourth of Nebraska is thus classified. Trees and 
even shrubs are not naturally very abundant in the sand hill region except 
along streams. In the planting a cue is taken from nature in the presence 
of Pinus ponderosa in the sand hill region; the occurrence of isolated tracts of 
this species suggests a former more extensive distribution. At the suggestion 
of Professor Bessey, the Forest Service began planting as far back as 1891. 
About ten years ago, large tracts of land capable of forestation were set aside 
as national forests, and nurseries were established at Halsey, Nebraska, and 
Garden City, Kansas. In the Nebraska nursery, attention has been paid to 
conifers, and success has been had especially with Pinus Banksiana and the 
native P. ponderosa. In the Kansas nursery, experiment has been made 
chiefly ail hardwoods.—H. C. Cow tes. 
The chemistry of symbiosis.—Not muck is known concerning the exact 
chemical interrelations of symbionts. To ZELLNER it is a matter of surprise 
that investigators of symbiosis have paid so little attention to this fundamen- 
tally important feature, and he indicates in a brief paper# some of the places 
where more knowledge is urgently needed. Best known, of course, are the 
are water-absorbing organs for the roots. In the endotrophic forms phago- 
39 Cannon, W. A., A note on a chaparral-forest relation at Carmel, California. 
Plant World 16:36-38. 1913. 
# Bates, C. G., and Pierce, R. G., Forestation of the sand hills of Nebraska and 
Kansas. Bull. 121, U.S. Forest Service. pp. 49. pls. 13. fig. I. 1913. 
ZELLNER, JULtus, Die Re der Pflanzen als chemisches Problem. Beih. 
Bot. ‘Cae 28': 473-486. 1 
