March 6, 1890] 



NATURE 



431 



An apparatus was described by means of which digestions can 

 be carried on in a dialyzer in such a way as to provide for the 

 constant motion of the digesting mixture and the removal of 

 digestive products : by this method a partial reproduction of 

 two of the most important factors in natural digestion is 

 provided. 



So far the method has been employed for 



I. The salivary digestion of starch. Experiments conducted 

 under otherwise similar conditions in the dialyzing digester and 

 a flask, showed that— (i.) The rate of digestion in the former is 

 always greater than in a flask, and at the same time the tendency 

 to the development of bacteria is greatly lessened, (ii.) The 

 amount of starch converted into sugar is always greatest in the 

 dialyzer. (iii. ) The total sugar formed and small residue (4"29 

 percent.) of dextrin left during an active and prolonged diges- 

 tion in the dialyzer justify the assumption that, under the more 

 favourable conditions existing in the body, the whole of the 

 starch taken is converted into sugar before absorption. 



The above results afford an explanation of the existing dis- 

 cordant statements as to the nature and amount of products 

 formed during starch digestion. 



II. The tryptic digestion of proteids. The experiments made 

 dealt chiefly with the formation of leucin and tyrosin, and were 

 undertaken, initially, in order to find out why these crystalline 

 products are formed in large amount during an artificial diges- 

 tion, while they have so far been described as occurring in mere 

 traces during natural digestion. The results of the experiments 

 made it probable that leucin and tyrosin should be formed 

 during natural digestion. Examination of the contents of the 

 small intestine during proteid digestion showed that, contrary 

 to existing statements, leucin and tyrosin are formed in not in- 

 considerable quantities during the natural process. 



The last part of the communication dealt with the probable 

 physiological importance of the formation of amidated bodies 

 during tryptic digestion, and a view was put forward as to the 

 possible and probable importance of amides in the chemical 

 cycle of animal metabolism. 



The experiments are being extended to the pancreatic digestion 

 of starch. 



Linnean Society, February 20. — W. Carruthers, F. R. S., 

 President, in the chair. — Mr. G. C. Druce exhibited specimens 

 of Agrostis canina, var. Scotica, and a small collection of flower- 

 ing plants dried after treatment with sulphurous acid and alcohol, 

 and showing a partial preservation of the natural colours of the 

 flowers. — Mr. F. P. Pascoe exhibited a series of Coleopterous 

 and Lepidopterous insects to show the great diversity between 

 insects of the same family. — The Right Hon. Sir John Lubbock, 

 Bart., M.P., P.C., then gave an abstract of four memoirs which 

 he had prepared : (i) on the fruit and seed of the Juglandise ; 



(2) on the shape of the oak-leaf: (3) on the leaves of Viburnum ; 

 and (4) on the presence and functions of stipules. An interest- 

 ing discussion followed, in which Mr. J. G. Baker, Mr. John 

 Fraser, Mr. D. Morris, and Prof. Marshall Ward took part. 



Edinburgh. 



Royal Society, February 17.— Sir W. Thomson, President, 

 in the chair. — Prof. Crum Brown communicated a paper, by 

 Mr. Tolver Preston, on Descartes' idea of space and Sir W. 

 Thomson's theory of extended matter. — The following communi- 

 cations from the chemical laboratory of the University were 

 read : — (a) Prof. Crum Brown, on a new synthesis of dibasic 

 organic acids. The method proposed was the electrolysis of 

 potassium ethyl salts of lower dibasic acids which would take 

 place according to the scheme 



2EtOOC.R".COOK = EtOOC.R".R".COOEt + 2C02 + 2K, 



thus giving the diethyl ether of a higher acid of the same series. 



(3) Prof. Crum Brown and Dr. James Walker, on the electrolysis 

 of potassium ethyl malonate, and potassium ethyl succinate. 

 The reaction actually takes place in great measure in the above 

 indicated sense, the yields of pure succinic ether and of adipic 

 ether respectively being from 20 to 30 per cent, of the theoretic- 

 ally obtainable quantities. The method is thus proved to be of 

 practical as well as of theoretical importance, {c) Dr. John 

 Gibson, on the action of bromine and carbonate of soda in 

 solutions of cobalt and nickel salts. — Mr. W. Calderwood read 

 a paper on the swimming bladder and flying powers of Dactylo- 

 pteriis volitans. 



Paris. 



Academy of Sciences, February 24. — M. Hermite in the 

 chair. — The proofs of the separation of the south-east extremity 

 of the Asiatic continent during recent times, by M. £mile 

 Blanchard. The author advances proofs from the resemblance of 

 animal and vegetable life in Further India, on the peninsula of 

 Malacca, and Sunda Islands.— The Dryopithecus, by M. Albert 

 Gaudry. The relation of Dryopithectts to the ape and to mar* 

 has been investigated. — A contribution to the chemical study of 

 the truffle, by M. Ad. Chatin. The researches have been 

 directed to the quantitative determination of the organic and 

 other matter in truffles. — Scrotal pneumoceles, by M. Vemeui). 

 — On the anatomy and the physiological pathology of the re- 

 tention of urine, by M. F. Guyon. — Transformations in kine- 

 matic geometry, by M. A. Mannheim. — On the constitution of 

 the line spectra of elements, by M. J. R. Rydberg. This is a 

 note on the periodic recurrence of doubles and triplets in the 

 spectrum of an element. It is shown how this periodicity 

 enables the spectrum of an element to be found by interpolation 

 when the spectra of elements of the same group are known, the 

 case of gallium being given as an example of the verification of 

 the principle. — Electrical oscillations in rarefied air, without 

 electrodes ; demonstration of the non-conductivity of the^ 

 vacuum, by M. James Moser. It is well known that vacuum- 

 tubes become luminous when near an induction coil in action. 

 The author, by enveloping one vacuum-tube with another, in. 

 which the rarefaction could be varied, finds that the excitation 

 may take place without any electrode. If the pressure in the 

 outer tube be equal to 760 mm., the inner tube, under the 

 influence of the coil, becomes luminous and of a clear blue 

 colour ; if, however, the pressure be diminished to i mm. of 

 mercury, the air in the outer tube becomes luminous and of a 

 pronounced red colour, thus reversing the phenomena. — Upon 

 the variation, with the temperature, of the bi-refractions of 

 quartz, barytas, and kyanite, by MM. Er. Mallard and 

 H. Le Chatelier. This variation has been studied by the 

 aid of a photographic spectroscopic method : with quartz 

 a singular point is detected at 570°, at which temperature the 

 law of variation suddenly changes ; a similar phenomenon is 

 indicated as occurring in the case of kyanite somewhere between 

 300° and 600°. — The vapour-pressure of acetic acid solutions, by 

 MM. F. M. Raoult and A. Recoura. It has been previously 

 shown by one of the authors {Comptes rendus. May 23, 1887 ; 

 Annales de Chimie et de Physique, 6th series, t. xv., 1888) that, 

 if/ represents the vapour-tension of a solvent for a certain tem- 

 perature, /' the vapour-tension under similar conditions when a 

 non- volatile body is in solution, P the weight of substance dis- 

 solved in 100 grms. of the solvent, M the molecular weight of 

 the dissolved body, and M' the molecular weight of the solvent, 

 then for dilute solutions — 



/'P 



K being a constant generally near to unity. Employing the 

 dynamical method, the mean value of K for acetic acid is found 

 to be I '61, taking 60 as the molecular weight of acetic acid; 

 but if the molecular weight of a liquid be the same as that of the 

 saturated vapour, the apparent anomaly disappears, for with 

 molecular weight 97 (deduced from density of saturated acetic 

 acid vapour at 118°, viz. 3"35), the above formula gives K=l. — 

 Theaction, in the dry way, of various arseniates of potassium and 

 sodium upon the oxides of the magnesia series, by M. C. Lefevre. 

 — Note on the volumetric estimation of copper, by MM. A. Etard 

 and P. Lebeau. A method of titration is given by the authors, 

 for which they claim a rapidity and accuracy comparable to the 

 permanganate method for iron ; it is based upon the formation 

 of a characteristic violet coloration on the addition of concen- 

 trated hydrobromic acid to a solution of the copper salt, and 

 the subsequent decoloration of the solution by standardized 

 stannous chloride solution containing much hydrochloric acid ; 

 thus — 



2CuBr„ + «HBr + SnBr, = SnBr4 + CugBra + ?/HBr. 



M 

 M'' 



Coloured. 



Uncoloured. 



— Preparation of hydroxycamphocarbonic acid from campho- 

 carbonic acid, by MM. A. Haller and Minguin. — Upon the or- 

 ganization of left-handed Prosobranchiate Gastropoda (Neptunea 

 contraria, Linnceus), by MM. P. Fischer and E. L. Bouvier. — 



