July i, 1S84] 



NA TURE 



227 



of the anterior pouch is almost identical in the two forms, for in 

 Balanoglossus its left-hand division becomes lined by cilia and 

 opens to the exterior, whereas its right-hand half degenerates 

 into connective tissue. And as regards the nervous system (which 

 in Balanoglossus contains no mesenteric canal as that of Amphi- 

 oxus does) " it is only necessary to imagine the invagination of the 

 dorsal nerve-cord to have been extended along the back (instead 

 of being confined to the region of the collar) in order to reproduce 

 the condition which is found in Amphioxus." But however much 

 we may be struck by these relations of Balanoglossus, its own 

 isolated position and the extreme difficulty of allying it to any 

 other Invertebrate groups prevent it from throwing much light 

 upon the Vertebrate pedigree. The claims of the two theories 

 discussed above may be unaffected, however close the corre- 

 spondence between Amphioxus and Balanoglossus may be shown 

 to be ; and as yet Balanoglossus seems to do little more than 

 remind us of how remote a relative of the Vertebrates Amphioxus 

 itself is. Amphioxus occupies such an outlying branch, so far 

 from the main stem of the genealogical tree of Vertebrates, that 

 the demonstration of its likeness to an isolated Invertebrate like 

 Balanoglossus may, like its obvious relationship with the Tuni- 

 cates, be of little use to us. 



It is perhaps premature to judge between these two theories 

 detailed above, or to accept either of them definitely as an indi- 

 cation of the origin of Vertebrates. But we must point out that 

 the Chaetopod theory lies under the great disadvantage of 

 1 - -liming as far distant ancestor of Vertebrates a class of animals 

 that seem really to occupy an apical position in a certain line of 

 development. The Chretopods seem to be so highly specialised, 

 that we must be suspicious of taking them to be the origin of 

 another great group, but rather consider them as the ultimate 

 result of evolution in a particular direction. In general it must 

 always, a piioii, be unsafe to attempt to make the apex of one 

 group the base of the next ; and in all cases it must be better, 

 and mure consonant with the principles of evolution, to search 

 for the closest relations of one group among the simpler and less 

 specialised members of another. A. E. S. 



THE ROYAL SOCIETY OF CANADA 

 '"FHE annual meeting of this Society was held at Ottawa, 

 *■ May 2t -24, under the presidency of the Hon. P. J. O. 

 Chauveau, L.L.D., D.-es-L. 



The following papers were read in Section III. (Mathemati- 

 cal, Physical, and Chemical Sciences) : — Electrical induction in 

 underground and aerial metallic conductors, by F. N. Gisborne, 

 CE. The author proposed, in order to get rid of induction 

 phenomena in telephone circuits, to connect sending and receiving 

 telephones by means of pairs of twisted and insulated wires. He 

 described experiments made with a section of cable about 3000 

 feet in length and laid underground between two of the Depart- 

 mental Buildings at Ottawa. The cable contained twenty indif- 

 ferently insulated wires, which were divided into pairs, iwo wires 

 being twisted together in each case, each pair constituting a 

 metallic circuit, and one wire of each pair being used as a 

 "return" instead of the earth plates usually employed. The 

 experiments showed that if one of these pairs was used as a tele- 

 phonic circuit, no induction effects could be observed in the 

 others. The absence of induction effect he attributed to the 

 equidistance of the two wires of a pair from any third wire and 

 the equality and opposition of the currents flowing in them. — A 

 particular case of the hydraulic ram or water hammer, by C. 

 Baillarge, C.E. — On the form of the contracted liquid vein 

 affecting the present theory of the science of hydraulics, by R. 

 Steckel. Communicated by C. Baillarge. C.E. — The origin of 

 crystalline rocks, by T. Sterry Hunt, LL.D., F.R.S. The 

 author began by remarking that the problem of the origin of 

 those rocks, both stratified and unstratified, which are made up 

 chiefly of crystalline silicates, is essentially a chemical one. He 

 then proceeded to review the history of the once famous dispute 

 between the vulcanist and the neptunist schools in geology as to 

 whether granite and other crystalline rocks were formed by 

 igneous or by aqueous agencies, and showed from recent writers 

 that the controversy is not yet settled. He noticed of the igneous 

 school both the plutonic and the volcanic hypotheses of the origin 

 of these rocks, and then considered the so-called mctamorphic 

 and metasomatic hypotheses, which would derive them by sup- 

 posed chemical changes from materials either of igneous or of 

 aqueous origin. The hypothesis of Werner was next discussed. 

 This conceives all such rocks to have been successively deposited 



in a crystalline form from a chaotic watery liquid, which sur- 

 rounded the primitive earth, and at an early time held in solution 

 the whole of the materials of these rocks. The inadequacy of 

 all of these hypotheses was pointed out, though it would appear 

 that Werner's was the one nearest ihe truth. The author con- 

 ceives that the crystalline rocks were formed by deposition from 

 waters which successively dissolved and brought from subter- 

 ranean sources the mineral elements. Their formation is illus- 

 trated by that of granitic veins, and that of zeolites — processes 

 regarded as survivals of that which produced the earlier rocks. 

 The Hue zeolites are but hydrated feldspars, while the minerals 

 of the pectolitic group correspond to the protoxyd-silicates of the 

 ancient rocks. The source of the elements in these rocks, 

 according to the new hypothesis here proposed, was in the super- 

 ficial layer which was the last-congealed portion of an igneous 

 globe consolidating from the centre. In this primitive stratum, 

 porous from contraction and impregnated with water, resting 

 upon a heated anhydrous nucleus, and cooled by radiation, an 

 aqueous circulation would be set up, giving rise to mineral 

 springs. The waters of these dissolved and brought to the 

 surface, there to be deposited, the quartz, the feldspars, and 

 other mineral silicates, which, through successive ages, built up 

 the great groups of crystalline stratified rocks, often so markedly 

 concretionary in aspect. Exposed portions of the primitive sili- 

 cated material would be subject to atmospheric decay and disin- 

 tegration, giving rise to sediments of superficial origin, which 

 would become intercalated with the deposits from subterranean 

 sources. The reactions between the mineral solutions from below 

 and the superficial materials were important in this connection, 

 probably giving rise to certain common micaceous minerals ; 

 while dissolved silicates allied to pectolite, by their reaction with 

 the magnesian salts, which then passed into the ocean waters, 

 generated species like serpentine and pyroxene. This process of 

 continued upward lixiviation of the primitive chaotic stratum 

 would result in the production of a great overlying body of strati- 

 fied acidic rocks, leaving below a basic residual and much 

 diminished portion, the natural contraction of which would cause 

 corrugations of the superincumbent stratified mass, such as are 

 everywhere seen in these ancient rocks. The source of volcanic 

 rocks is partly in this lower and more or less exhausted stratum 

 of comparatively insoluble and basic ferriferous silicates, whence 

 come melaphyres and basalts ; partly in the secondary or acidic 

 mass, which, softened by the combined agency of water and heat, 

 may give rise to granitic and trachytic rocks ; and partly also, it 

 is conceived, in later aqueous deposits of superficial origin, which 

 also may be brought within the influence of the central heat. 

 This attempt to explain the genesis of crystalline rocks by the 

 continued solvent action of subterranean waters on a primitive 

 stratum of igneous origin the author designates the crenitic 

 hypothesis, from the Greek ttp-hvn, /"»'■ A preliminary state- 

 ment of it was made by him to the National Academy of Sciences 

 at Washington, April 15, 1884, and appears in the American 

 Naturalist for June.— On the density and thermal expansion of 

 aqueous solutions of copper sulphate, by Prof. J. G. MacGregor, 

 D.Sc. The author gave the results of extended observations "f 

 the density of solutions of different concentration and at different 

 temperatures. They show that the rate of variation of density 

 with temperature increases with the temperature and with the 

 percentage of salt in solution ; that the density of any solution at 

 low temperatures (below 20 C.) diminishes, as the temperature 

 increases at a greater rate than that of water ; that the ratio of 

 the density of a solution to the density of water at the same tem- 

 perature diminishes as the temperature increases ; and certainly 

 for many solutions, probably for all, attains a constant value 

 within the temperature limits of the experiments (below 35 - 5p°) ; 

 that, therefore, at about 40 C. the thermal expansion of solutions 

 is the same as that of water at the same temperature. The expe- 

 riments also substantiated a result formerly reached by Prof. 

 Ewing and the author that very weak solutions of this salt have 

 a smaller volume than the water used in making them. If then 

 these solutions are made by the addition of anhydrous salt to 

 water contraction must occur. The experiments show that the 

 greatest contraction occurs in the case of a solution containing 

 I -34 per cent, of anhydrous salt, in which case the contraction is 

 0-0048. The solution containing 5-95 per cent, of anhydrous 

 salt has the same volume as the water required to make it.— 

 Blowpipe reactions in plaster of Paris tablets, by Prof. E. 

 Haanel, Ph.D. This paperwas a continuation of that presented 

 to- the Society last year. The author described the result of the 

 treatment of copper with hydrobromic acid, and of iron and 



