SOCIETIES AND ACADEMIES. 
LONDON. 
Royal Society, June 12.—‘‘On the Parasitism of 
Pseudomonas destructans (Potter).” By M.C. Potter, M.A. 
F.L.S., Professor of Botany in the University of Durham 
College of Science, Newcastle-upon-Tyne, Communicated by 
Sir Michael Foster, K.C.B., Sec. R.S. 
The author gives an account of his further study of the action 
of the cytase and toxin, secreted by this bacterium, upon the 
living turnip cell ; and he has succeeded in tracing the passage 
of the bacterium into the cells, through the cell-wall. The 
observations were made from pure cultures, under the most 
rigid sterile conditions, by means of the hanging drop. The 
action of the cytase and toxin was surprisingly rapid; the 
swelling of the cell-wall and contraction of the protoplasm 
could be observed almost immediately, upon the introduction 
of the Pseudomonas. Within an hour and a half the cell was 
dead and its walls in an advanced stage of disintegration. 
The original cell was kept under observation for some days, 
and after patient and continuous watching certain of the bacteria 
were observed slowly forcing their way through the wall, until 
finally they emerged into the cell-cavity. The penetration of 
the wall was observed on several occasions, and numerous in- 
dividuals could be seen in all stages of the process. The time 
required varied with the thickness of the wall, but on an average 
occupied about three hours. 
Important evidence of the perforation of the cell-wall by 
P. destructans was also afforded by the method of paraffin 
sections ; by fixing and double staining, the cell-wall and bacteria | 
were distinctly differentiated, the latter being shown fixed in the 
actual process of perforating the wall, and various stages of 
penetration could be distinguished. 
Experiments showed that the old and fully developed cuticle 
is apparently proof against the action of the enzymes excreted 
by P. destructans, but this parasite can readily effect an entrance 
into its host through the undeveloped epidermis of young and 
tender structures. 
A comparison of the parasitism of Botrytis cinerea, as 
demonstrated by Nordhausen, presented an exact parallel. The 
point was established that this bacterium has the power of 
destroying the living cells of the turnip, and, subsisting upon 
their dead contents, continues to work its way through the host, 
and it thus acts in precisely the same manner as one acknowledged 
parasitic fungus. 
Chemical Society, June 18.— Elimination of a nitro-group 
on diazotisation. Dinitro-f-anisidine, by Prof. Meldola and Mr. 
. V. Eyre. When dinitro-f-anisidine is diazotised in presence 
of hydrochloric acid the 3-nitro-group is replaced by chlorine. 
—Preliminary notice of some new derivatives of pinene and 
other terpenes, by Prof. Tilden and Dr. H. Burrows, Pinene 
nitrosochloride, when treated with potassium cyanide in 
alcohol, is converted into pinene nitrosocyanide, a colourless 
crystalline substance melting at 171°. The latter reacts readily 
with various reagents, furnishing well-crystallised reaction pro- 
ducts.—The colour-changes exhibited by the chlorides of cobalt 
and some other metals from the standpoint of the theory of 
electro-affinity, by Messrs. Donnan and Bassett. These colour- 
changes are shown to be due to the gradual dissociation of the | 
complex molecules of the salts.—The stereochemical formula 
of benzene, by Mr. Marsh. A discussion of the various possible 
space formule of benzene and a reply to Graebe’s objections to 
the stereocentric representation.—An accurate method of deter- 
mining the compressibility of vapours, by Dr. Steele. A de- 
scription of a special apparatus devised for this purpose. —A new 
type of substituted nitrogen chlorides, by Dr. Chattaway. The 
author describes a group of these substances containing three 
negative radicles directly attached tothe nitrogen atom, such as 
dibenzoy] nitrogen chloride, (C;H;CO).:N.Cl.—The preparation 
of pure chlorine and its behaviour towards hydrogen, by Messrs. 
J. W. Mellor and E, J. Russell. The chlorine was prepared by 
electrolysis of fused silver chloride, and the hydrogen by the 
action of steam on sodium. Mixtures of these gases were found 
to be exploded by electric sparks even after several months’ 
drying over phosphorus pentoxide.—Derivates of dibenzoyl 
mesitylene, by Mr. W. H. Mills and Dr. Easterfield.—The 
molecular condition of borax in solution, by Mr. H. S. Shelton. 
The author, from a series of measurements of electric conductivity 
of borax solution of diminishing concentrations, shows that 
hydrolysis into boracic acid and sodium hydroxide occurs to the 
NO. 1705, VOL. 66] 
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[JuLy 3, 1902 
extent of 4 per cent. at 25°.—On the union of hydrogen and 
chlorine, v. and vi., by Dr. Mellor. The author concludes that the 
chemical change occurring when moist chlorine is exposed to 
sunlight is due to interaction between the chlorine and the 
moisture contained in it. No intermediate compound, such as 
hypochlorous acid or chlorine monoxide, seems to be formed.— 
On some hydroxy-pyrone derivatives, by Messrs. Tickle and 
Collie. A description of hydroxydimethylpyrone and hydroxy- 
comenic acid obtained by oxidising dimethylpyrone and meconic 
acid respectively with hydrogen peroxide.—The absorption 
spectra of phloroglucinol and some of its derivatives, by Messrs, 
Hartley, Dobbie and Lauder. The absorption spectra of 
phloroglucinol and its winrethyl ester are almost identical, 
whence it follows that the parent substance possesses an enolic 
structure, —Solubility of mannitol, picric acid and anthracene, 
by Dr. Findlay. An investigation of the general applicability 
of the rule recently observed by the author connecting the 
solubilities of substances. — Menthyl formylphenylacetate, by 
Messrs. Cohen und Briggs. A description of the principal 
properties of this substance is given differing in some points from 
those assigned to it by Lapworth and Hann.—Transformation of 
diacetanilide into aceto-p-aminoacetophenone, by Dr. Chat- 
taway.—Nitrogen chlorides and bromides derived from ortho- 
substituted anilides, by Dr. Chattaway and Mr. Wadmore. 
A description of severai members of this class obtained by the 
interaction of hypochlorous and hypobromous acids with the 
corresponding anilides.—Substituted nitrogen chlorides con- 
taining the azo-group, by Dr. Chattaway.—The action of 
chlorine and bromine on nitroaminobenzenes, by Dr. Orton. 
A description of sy7z. trisubstituted chloro- and bromonitroamino- 
benzenes obtained by the interaction of the above substances. — 
The transformation of diazoamido- into aminoazo-compounds 
and of hydrazobenzene into benzidine, by Dr. Chattaway. A new 
method of formulating these changes is suggested. —Tribromo- 
phenolbromide, by Mr. KE. W. Lewis. The melting point of 
this substance when pure is 148°, not, as generally stated, 118°. 
Royal Astronomical Society, June 13.—Dr. J. W. L. 
Glaisher, president, in the chair.—M. Bigourdan gave an 
account of the long series of observations of nebulz which he 
is making at the Paris Observatory, his aim being to obtain 
accurate micrometric measures of a large number of nebule. 
M. Bigourdan presented to the Society two volumes of his ob- 
servations, and also the volume of Pingré’s ‘‘ Annales Célestes,” 
which the author had left in MS., and which M. Bigourdan had 
now edited and published. —Dr. Downing read a paper on the dis- 
tribution of the stars in the Cape Photographic Durchmusterung,. 
He had reduced the places of the stars to galactic coordinates, 
to investigate their distribution with reference to the Galaxy. 
The results showed a ring of bright stars nearly in the Galactic 
plane, stars in the groups mag. 6°5 to 7°0 being more uniformly 
distributed. After magnitude 8’o there isa greater difference 
between the density of the polar and equatorial zones of the 
Galaxy. The Cape Durchmusterung agrees with the Bonn 
Survey in assigning an ellipsoidal form to the visible universe. — 
| Mr. Thackeray read a paper on a comparison of Groombridge’s 
and Struve’s right ascensions of close circumpolar stars, pre- 
facing it with an account of the life of Stephen Groombridge, 
The paper was accompanied by atable showing, from an inde- 
pendent comparison of a certain number of Groombridge’s stars, 
that the probable error of an observation is about Os. ‘053.—Mr. 
Filon read a paper on reduction of measures of Swift's comet 
(a 1899) from photographs taken with a portrait lens of 30-inch 
focus and 5-inch aperture. Apart from the intrinsic value of the 
comet places, it appeared of interest to determine the degree of 
accuracy obtainable from measures of stars on plates taken with 
an ordinary portrait lens, and to find if photographs thus taken 
would repay the labour of measurement and reduction. The 
author concluded that such plates can give star places accurate 
to about 0”°83 of arc.—Mr. Hinks read a paper on the reduc- 
tion of photographs of Eros for the determination of solar 
parallax. He concluded that the direct comparison of simul- 
taneous photographs by linear reductions is the most convenient 
method. He desired to propose that seven or eight observatories, 
spread over as long an arc of longitude as possible, should 
agree upon a common list of comparison stars, and measure all 
their plates taken within a period of nine days. It might then 
be possible to find out in two or three years whether Eros will 
give as good results for parallax as other less favourably situated 
minor planets.—A paper by Mr. H. C. Plummer, on the prin- 
ciple of the arithmetic mean, and other papers, were taken as read. 
