574 
terium. The author was able to produce 
the disease by inoculation in healthy plants. 
Owing to the care with which the Hollanders 
inspect their exportations the disease is 
unknown in this country. 
Dr. Smith described another bacterium, 
Bacillus Phaseoli, with related species, show- 
ing that this organism is a serious disease 
of garden and field beans. Thermal and 
cultural relations were shown, likewise 
drawings, photographs and macroscopical 
preparations, all aiding in the identification 
of the species. 
The same author discussed the relations 
of the brown color of humus soils to the 
pigment produced by Bacillus solanacearum, 
suggesting that this coloration of soils may 
be due to the action of bacteria in splitting 
up the carbohydrates of the humus. The 
isolated pigment will not serve as nutrient 
material for bacteria. 
Mr. C. A. Peters’ report of the formation 
of the reproductive organs of Drosera 
showed some details of pollen-origin and 
structure differing from those in most di- 
cotyledons. 
Dr. Schlotterbeck reported that accord- 
ing to his study the appendage to the seed 
of Melampyrum pratense is not a strophiole, 
nor a caruncle, nor an arillus, each of which 
has been claimed, but is a part of the en- 
dosperm which becomes constricted off from 
the rest during development. The same 
author has found the nucellus of Croton 
Tiglium protruding far out of the micropyle, 
the only other similar case known being 
that of Croton flavens. 
In the development of the pollen of the 
common milkweed, Asclepias cornuti, Profes- 
sor Spalding reported the work of Miss 
Langdon as showing some errors in the 
published account by Corry, especially re- 
garding the origin of the pollen-mother- 
cells and the outer wall of the pollinia. 
Peculiar changes in the protoplasm of the 
tapetal cells were also discussed with ref- 
SCIENCE. 
[N. S. Von. VI. No. 146. 
erence to their physiological significance. 
In the discussion which followed, the ques- 
tion arose as to what cells are to be denomi- 
nated pollen-mother-cells in this plant— 
whether the cells that by division into four 
give rise to the pollen-grains, or whether 
these four daughter-cells themselves are the 
pollen-mother-cells. 
Dr. Anderson reported the discovery o 
stomata on the bud-scales of Abies pectinata. 
What gives peculiar significance to this 
discovery is the fact that heretofore stomata 
have been thought never to occur on the 
bud-seales of Gymnosperms. 
The paper by the same author on the 
comparative anatomy of normal and dis- 
eased organs of Abies balsamea showed dif- 
ferences in structures of leaves of the lateral 
and erect branches ; the presence of 2 to 6 
resin canals in the bud-scales from which 
the resin, exuding through fringing hairs, 
spreads in a layer 1 to 3 mm. thick over the 
scale; the formation of resin-vesicles in 
the primary cortex by the growth of the 
epithelial lining to the resin canals. 
Dr. Townsend’s paper on the correlation 
of growth and injury narrated experiments 
with seedlings, larger plants and with Phy- 
comyces nitens. The injuries were given by 
excising parts of the plant, or by incisions. 
In Phycomyces there was a sudden retarda- 
tion of growth after cutting, and the normal 
rate was regained after 30 to 60 minutes. 
In higher plants there ensues on severe in- 
jury a gradual retardation, followed by a 
gradual regain of normal rate, a period of 
acceleration sometimes preceding. In seed- 
lings, especially, a rather slight injury 
caused an acceleration in 6 to 24 hours, 
with a subsequent fall to the normal rate. 
The distance through which the injury may 
influence the rate of growth may amount to 
several hundred millimeters. The amount 
of variation in rate of growth may equal 
80 % of the normal rate. 
‘The Mechanism of Root Curvature’ 
