478 



NA TURE 



\_MaTch 17, 1887 



In acklition to these varieties a description has been given for 



the sake of comparison of some aerial micro-organisms which 



were obtained by one of the authors from Dr. Koch's laboratory 



in Berlin. These are — 



Micrococcus rosaceus 



Sarcina Intea 



,, aurantiaca 



Bacillus subtilis 



,, (Micrococcus) prodi- 

 giosus. 



Linnean Society, March 3. — Mr. W. Carruthers, F.R.S., 

 President, in the chair. — The following gentlemen were elected 

 Fellows of the Society :— B. S. Dyer, Right Hon. Sir E. Fry, 

 S. T. Klein, C. Maries, E. S. Marshall, R. Morgan, J. B. 

 Stone, and A. W. Tait. — A paper was read by Mr. Alfred W. 

 Bennett on the genetic affinities and classification of the Algae. 

 He referred to Prof. Sachs's scheme as based on the mode of repro- 

 duction and degree of complexity of the sexual process alone ; 

 this being the most important factor in the life-history of the 

 plant. Supporting Sachs to a certain extent, he nevertheless 

 differs from him, and rather ag'rees with Prof. Fischer's view of 

 Alga; and Fungi running in distinct series, while he diverges from 

 both writers as to the descent, relations, and grouping of the 

 Algre. He believes arrest of development has had an important 

 influence in many presumed deviations among the groups in 

 question. He avers that retrogression may take the form of the 

 suppression of either the vegetative or the reproductive organs, 

 and whichever predominates or progresses leaves the other feeble 

 or degenerate. If the principle advocated by the author holds 

 good, it leads towards the ahnost abandoned divisions of the 

 Algae into the green, the red, and the brown, — Chlorosporese, 

 Rhodospore.-c, and Phzeosporeas. It would appear as if at an 

 early period in the development of the simplest form of 

 vegetative life, three kinds of cell-contents were represented, a 

 colourless, a blue-green, and a pure green. Based thereon are 

 the author's three great divisions : — T. Sckizomycetcs, forms 

 entirely destitute of chlorophyll, and adapted to carry on only a 

 parasitic existence ; II. Chroococcacar, unicellular organisms, 

 with cell-contents composed of w.atery blue-green endochrome 

 diffused through the protoplasm, without distinct chlorophyll 

 grjiins, starch grains, or nucleus ; III. Protococcacia, character- 

 ised by cells possessing a nucleus, starch grains, pure chlorophyll 

 identical with that of higher plants, and in certain states a true cell- 

 wall of cellulose. The (I.) Schizoraycetes lead to the Fungi, 

 which are not discussed by the author. The (II.) Chroococcaceoe 

 pass through the Oscillarieacea: to Nostocacece. The (III.) 

 Protococcaceze are the great derivatives of the Algal group. Hence 

 three great lines of descent are indicated, (i) The Diatoms are 

 regarded as of remote origin, very low in the scale. (2) The 

 Coeobiae comprise a series through Sorastrese to Volvox and 

 Allies. (3) The Eremobioe .as a line of descent pass to the 

 Multinucleate, e.g. Siphonea; with gigantic cells. Thence cell- 

 division originating, proceeded to the Confervoidere-isogama;, 

 the Conferva group. From these in three different lines have 

 sprung : (n) the Conjugate, including Zygnemids .and Desmids, 

 a retrogressive group ; {b) the brown se.aweeds adapted to deep 

 sea life, Phseosporece, terminating in Fucacere ; and (c) the 

 Confervoide^e-heterogamese, at the extreme of which the 

 ColeochjEta: are reached. The Coleochrcta; lead direct to the red 

 seaweeds, or Florid eas, a natural group with great variety in 

 development of the sexual organs. By arrest of development 

 branches proceed on the one hand through Nemaliece to the 

 Ulvacea;, while on the other at a tangent from true Algfe were 

 evolved the Characes, the Mosses, the Gymnosperms, and lastly 

 the higher Angiosperms, or flowering plants. — A paper was read 

 on the di^^ease of Colocasia in Jamaica, by Mr. G. Massee and 

 Mr. D. Morris. The negroes of the West Indies give the name 

 " Cocoes" to the main stem and shoots of a species of Aroid. 

 This forms a wholesome food, and is .<aid to be preferable to 

 yams and sweet potatoes. A blight arises in the tubers similar to 

 the potato-disease ; and as shown by the authors this is pro- 

 duced by a fungus belonging to the genus Peronospora, a new 

 species named by them P. triclwtoma. Instructions are given as 

 to remedial measures, an important one being the absolute 

 necessity of b.adly affected plants being wholly destroyed. 



Physical Society, February 26. — Prof. W. G. Adams, Vice- 

 President, in the chair. — The resolurion passed at the meeting 

 on February 12, providing greater facilities to persons being 

 abroad for qualifying for membership of the Society, was unani- 

 mously confirmed.— Prof. W. Stroud and Mr. A. S. Gulbenkian 

 were elected Members of the Society. — Mr. James Swinburne 

 read a note on Prof. Carey Foster's method of measuring the 



mutual induction of two coils. The author described an appar- 

 atus devised last summer for measuring mutual induction by a 

 null method, thus dispensing with a ballistic g.alvanometer. The 

 induction in the secondary coil is balanced by an opposite effect 

 produced by a variable known fraction of the primary current 

 passing through one wire of a double-wound coil of known 

 mutual induction, the other wire of which is joined in series with 

 the secondary coil and galvanometer. In a preliminary trial, 

 using an ordinary reflecting galvanometer, it was found that 

 instead of no deflection being observed, two kicks in opposite 

 directions occurred when there was iron in the circuit. A new 

 galvanometer, with heavy needle, is now being constructed to 

 overcome this difficulty. K null method of finding the ohm by 

 means of a differentially-wound, heavy-needle galvanometer is 

 suggested in the latter part of the note. Prof. Ayrton pointed 

 out that Prof Foster's method does not require readings on a 

 ballistic galvanometer, and mentioned that in practice it is 

 greatly superior to tho-e given in Maxwell and the ordinary text- 

 books. The chief drawback is the necessity of having large 

 condensers of accurately known capacity where large coefficients 

 are concerned. A large number of experiments have been 

 carried out at the Central Institution by Mr. Sumpner with very 

 satisfactory results. Prof, .\dams concurred in Prof. Ayrton's 

 statement regarding the difficulties in using Maxwell's methods 

 in practice, and expressed his satisfaction with the great simplicity 

 of Prof. Foster's method. — On the determination of coefficients 

 of mutual induction by means of the ballistic galvanometer and 

 earth inductor, byR. H. M. Bosanquet. The methods described 

 depend on two measurements of the throws of a ballistic galvano- 

 meter : (i) that produced by the sudden rotation of a coil (the 

 constants of which ai'e accurately known) through 180° about a 

 vertical axis ; and (2) that produced by the mutual induction to 

 be measured when a current of known strength is started in the 

 prim.ary circuit. The earth induction-coil is permanently joined 

 in series with the ballistic galvanometer and secondary coil, and 

 the primary current measured by an absolute tangent galvano- 

 meter of the Helmholtz pattern. If (3q and Q be the quantities 

 of electricity which pass through the ballistic galvanometer in 

 the two experiments, then 



_ 2NAH 

 (Jo j^ > 



where N A is the effective area of the inductor, and 



where C= CZ/tan S. 



.- O A/fftanfl a 



Hence ^ — — = - , 



(?„ 21VA $ 



where a and ;3 are the throws of the ballistic galvanometer. 

 From the above we get 



B G tan e 



A modification to be used when Af or /! are very large is also 

 described. Numerical results obtained are given, from which it 

 is inferred that Maxwell's formuKi; for calculating the mutual 

 induction of two circular coils cannot be applied where the 

 distance between their central planes is at all comparable with 

 their radii. Experiments on an A Gramme dyn.amo gave very 

 irregular results when the currents were small, owing to the sub- 

 permanent magnetism of the machine. Further uses of the 

 method are suggested, such as the absolute detemiin.ation of 

 capacity and resistance. Remarks on the subject were made by 

 Prof. Carey Foster and Mr. Swinburne, and Prof, .\yrton replied 

 to Mr. Swinburne's contention that Prof. Foster's method was 

 not independent of observations of a ballistic galvanometer (since 

 capacities are determined by their means) by pointing out that 

 where accurate standards exist it is quite legitimate to b.ase other 

 absolute measurements on them. — Prof Reinold then re.id ,an 

 abstract of a paper on the continuous transition from the liquic 

 to the gaseous state of matter at all temperatures, by Prof. W. 

 Ramsay and Dr. Sydney Young. The authors find the relation 

 between pressure and temperature of gases .and liquids at con- 

 stant volume expressible by p - bt - a where b and a are 

 constants, and therefore conclude that the isochors {i.e. curves 

 connecting/ and ^ for constant volume) .are straight lines. At 

 temperatures below the critical point, the isotherm, during passage 

 from the gaseous to the liquid state, is a serpentine curve inter- 



(?=■ 



