pec. 4, 1923 PROCEEDINGS: BOTANICAL SOCIETY 451 
World field; such participation would be welcomed and would exert a whole- 
some, stimulating influence in many directions. 
The lecture was illustrated by charts and by photographs of a series of the 
most important localities where ancient skeletal remains of man were 
discovered. 
WiuuiaM R. Maxon, Recording Secretary. 
THE BOTANICAL SOCIETY 
165TH MEETING 
The 165th meeting was held-at the Cosmos Club, February 6, 1923, at 
8 p.m. with Dr. H. L. SHantz in the chair, and 31 persons present. 
Program: Dr. PERLEY SPAULDING: Notes on some tree diseases in Europe. 
(Illustrated.) Melampsorella elatina causes cankers on the trunks of Abies 
pectinata which greatly reduce the timber value. Fomes annosus causes root 
rot especially of Abzes pectinata, in some places preventing the use of this 
species. Cronartium ribicola is generally distributed in Europe wherever 
Pinus strobus occurs. It is exterminating this species as well as P. monticola 
and P. flexilis, both of which are more susceptible than is P. strobus. Pinus 
excelsa is quite resistant and may well be substituted for P. strobus, not only 
in Europe but in North America. Trees of P. strobus from 4 to 118 years of 
age were killed by this fungus, age giving no degree of immunity. Dasyscypha 
willkommii attacks the larches in Great Britain, but a new hybrid larch is 
not only immune to this disease but is the fastest growing larch known there. 
Robinia pseudacacia, wrecked in America by Fomes robinzae and a wood borer, 
is a real tree in Europe because these two enemies have been left behind in 
America. 
N. Rex Hunt: Steam and chemical soil disinfection. A cheap, effective, 
practicable method of soil disinfection is needed to exterminate the potato 
wart disease before it spreads to important potato growing regions. Potato 
wart extermination methods were studied at Freeland, Pa., and Washington, 
D. C., 1920-22 by F. G. O’Donnell, Rush P. Marshall, and the speaker. 
The inverted steam-pan method was found fairly effective but expensive and 
impracticable for large scale use. A pressure regulator was found to insure 
more uniform treatment of soil. Soil temperature changes brought about by 
steaming were determined. Fourteen chemical treatments, ranging upward 
from $250.00 per acre in cost, were found effective against wart, mercuric 
chloride, borax, chloride of lime, copper sulphate, sodium carbonate, sodium 
fluoride, and. sulphur were used dry. Kerosene and crude oil were used un- 
diluted. Effective solutions were mercuric chloride, Bordeaux, cleaning solu- 
tion, lime sulphur, sodium chromate, and Fairmount weed-killer. Some 
chemicals were applied to the surface and some were worked into the soil. 
The variable growth of potato plants in these treated plots is recorded. Ihe 
effect of the treatments on the hydrogen-ion readings of the soil was record- 
ed. A study of the effect of treatments on the soil flora was begun. 
The influence of soil moisture and soil type on the penetration of some 
chemicals was determined and found to be very important. The addition 
of sodium chloride increased the penetration of mercuric chloride remarkably. 
Better penetration and more uniform distribution of this solution is secured 
by applying all chemicals in part of the water, and then applying the re- 
mainder of the water. Kerosene penetrates several times as well in damp as 
in dry soil. .The various groups of data secured have a very practical bearing 
