3io 



NA TURE 



[July 26, 1888 



Bulletin de V Academic Royale de Belgique, May. — On the new 

 elements of the orbit of Eucharis, by L. de Ball. Continuing 

 his researches on the elements of this planet (181), the author 

 here establishes two new normal positions by means of the 

 observations made in 1886 and 1887. He also revises the posi- 

 tions of the comparison stars, and resumes the calculation of the 

 perturbations caused by Jupiter, Saturn, and Mars, utilizing for 

 the last named the results of Asaph Hall's observations on the 

 satellites. — Contribution to the study of pulsation in the lower 

 animal organisms, by Dr. De Bruyne. The results are given of 

 the author's studies on the pulsating function of an encysted 

 Protozoon obtained in abundance by culture, but of not yet 

 determined family. From his minute observations on the for- 

 mation, development, and action of the vesicle endowed with 

 rhythmical motion, he concludes that this organ has no com- 

 munication with the periphery, and has nothing to do with the 

 digestive function, as is commonly supposed, but is a true organ 

 of respiration and circulation, a heart and lung combined. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, May 31.—" The Conditions of the Evolu- 

 tion of Gases from Homogeneous liquids. " By V. H. Veley, 

 M.A., University College, Oxford. 



In Part I. an account is given of the effect of finely divided 

 particles on the rate of evolution of gases resulting from chemical 

 changes ; in Part II. the phenomenon of initial acceleration, as 

 also the effect of variation of pressure on the evolution of gases, 

 is discussed ; in Part III. the case of the decomposition of formic 

 acid into carbonic oxide and water is investigated under constant 

 conditions, other than those of the mass of reacting substances 

 and of temperature. 



Part I. — It is found that the addition of finely divided chemi- 

 cally inert particles increases the rate of evolution of gases from 

 liquids in which they are being formed. . The effect of these 

 particles on the following chemical changes is investigated : 

 (i.) the decomposition of formic acid yielding carbonic oxide ; 

 (ii.) the decomposition of ammonium nitrite in aqueous solution 

 yielding nitrogen ; (iii.) the reduction of nitric acid into nitric 

 oxide by means of ferrous sulphate ; (iv.) the decomposition of 

 ammonium nitrate in a state of fusion producing nitrous oxide ; 

 and (v.) the decomposition of potassium chlorate in a state of 

 fusion producing oxygen. The finely divided substances used 

 are pumice, silica, graphite, precipitated barium sulphate and 

 glass-dust. 



Part II. — It is observed that, conditions of temperature re- 

 maining the same, the rate of evolution of a gas from a liquid 

 is at first slow, then gradually increases until it reaches a maxi- 

 mum, and for some time constant, rate. From this point the rate 

 decreases proportionally to the diminution of mass. This is ob- 

 served in the cases of decomposition of formic acid, potassium 

 ferrocyanide, and of oxalic acid by concentrated sulphuric acid, 

 and in that of ammonium nitrate. It has previously been ob- 

 served in the case of the decomposition of ammonium nitrite in 

 aqueous solution. The same phenomenon repeats itself when 

 the temperature is temporarily lowered and then raised to its 

 former point, and also to a more marked degree when, tem- 

 perature remaining the same, the superincumbent pressure is 

 suddenly increased. 



The reduction of pressure from one to a fraction of an atmo- 

 sphere produces no permanent effect on the rate of evolution of a 

 gis from a liquid ; a decrease of pressure, however, produces 

 temporarily an increase in the rate, and an increase of pressure 

 conversely produces temporarily a decrease in the rate. 



Part III. — The case of the decomposition of formic acid into 

 carbonic oxide and water by diluted sulphuric acid is studied 

 with the aid of an apparatus by means of which the temperature 

 is kept constant within one-twentieth of a degree. It is shown 

 that the rate of evolution of carbonic oxide is expressible by the 

 following equation — 



log (r + t) + log r — log c, 



in which r is the time from the commencement of the observa- 

 tions ; t is the interval of time from the moment of commence- 

 ment, and that at which, conditions remaining the same, the 

 interval of time required for unit change would have been nil ; 

 r is the mass at the end of each observation, and c is a constant. 



The results calculated by this hypothesis agree with those ob- 

 served, whether the interval of time required for unit change 

 is 30 or 960 minutes. The curve expressing the rate of chemical 

 change in terms of mass is thus hyperbolic and illustrative of 

 the law — 



dr r 1 - 



which expresses the rate at which equivalent masses act upon one 

 another ; i/c in each experiment is the amount of each unit mass 

 which reacts with the other per unit of time, when a unit mass 

 of each substance is present. Since, then, equivalent masses 

 take part in the change, it is reasonable to suppose that at first 

 an anhydride of formic acid is produced, which is subsequently 

 decomposed into carbonic oxide and water. 



The change may thus be compared to the production of ethyl 

 formate from formic acid and alcohol, with which it shows 

 several points of analogy. 



June 14. — "The Electric Organ of the Skate. Structure and 

 Development of the Electric Organ of liaia radiata." By J. C. 

 Ewart, M.D., Regius Professor of Natural History, University 

 of Edinburgh. Communicated by Prof. J. Burdon Sanderson, 

 F.R.S. 



The first part of this paper is chiefly devoted to a comparison 

 of the electric organs of Raia radiata, Raia batis, and Raia cir- 

 cularis. It is shown that the organ in the species radiata differs 

 in many respects from the organ in the twj other species, and 

 that an exhaustive study of its structure and development is 

 likely to throw considerable light on the nature of electric organs 

 generally, and also on the structure of the motor plates of muscles. 

 While Raia batis may reach a length of over 180 cm., Raia 

 radiata seldom measures more than 45 cm. from tip to tip, and 

 is thus only about half the size of a large Raia circularis. In Raia 

 radiata the electric organ is absolutely and relatively extremely 

 small. In Raia batis the electric organ may be 60 cm. in length 

 and 7 cm. in circumference at the centre, and extend from the 

 skin to the vertebral column, but in an adult Raia radiata the 

 organ is seldom over 13 cm. in length and 8 mm. in circumference, 

 and the posterior two-thirds is confined to a narrow cleft between 

 the skin and the great lateral muscles of the tail. Further, the 

 organ of Raia radiata consists of minute shallow cups, which 

 only remotely resemble the large well-formed electric cups of 

 Raia circularis. In the latter species the various layers of the 

 electric cup are readily comparable to the more important layers 

 of the electric disk of Raia batis, but in Raia radiata the electric 

 cup is little more than a muscular fibre, with one end expanded 

 and slightly excavated to support a greatly enlarged motor plate, 

 in which terminate numerous nerve-fibres. The striated layer of 

 Raia batis and circularis, which consists of characteristic lamellae, 

 having an extremely complex arrangement, is entirely absent 

 from Raia radiata, the electric layer is indistinct, and instead of 

 a thick richly nucleated cortex, the cup is merely invested by a 

 slightly thickened sarcolemma. Further, the tissue forming the 

 shallow, thick-walled cup, both in its appearance and consistency, 

 closely resembles an ordinary muscular fibre, while the long stem 

 usually remains distinctly striated to its termination. 



In the second part of the paper an account is given of the 

 development of the electric cups of Raia radiata. It is shown 

 that the rate of development compared with Raia circularis, 

 but more especially with Raia batis, is extremely slow. The 

 young radiata is nearly double the size of the batis embryo before 

 the muscular fibres reach the "club" stage, and the long nearly 

 uniform clubs, instead of at once developing into rudimentary 

 cups as is the case in batis, assume the form of large Indian clubs. 

 When the young skate reaches a length of about 35 cm., the 

 long secondary clubs begin to expand anteriorly, and this ex- 

 pansion continues until a fairly well-moulded cup mounted on a 

 long delicate stem is produced. But the process of conversion 

 is scarcely completed when the skate has reached a length of 40 

 cm., i.e. when it has nearly reached its full size, for in the 

 species radiata a length of 50 cm. is seldom if ever attained. 



The cup-stage having been eventually reached, the stem, which 

 for a time may still increase in length, is often compressed by 

 two or more cups being closely applied together, and part of the 

 rim of the cup may be slightly everted or projected forwards, 

 but even in the largest specimens of Raia radiata examined there 

 was never any indication of retrogressive changes. 



The small size of the electric organ, together with the shallow- 

 ness of the minute cups of which it consists, seems at first to 

 indicate that in Raia radiata we have an electric organ in the 



