Jui.v I I, 1895] 



NATURE 



261 



(7) The progress of secular extinction of species and other 

 divisions of the animal and vegetable kingdoms, including the 

 types which s])ecially characterise the various stages and suli- 

 stagcs of the geological scale, was accelerated by adverse changes 

 of environing c<mditions, and were retarded liy a continuance of 

 congenial conditions. The final consummation of the extinction 

 • if the types was naturally often, and perhaps usually, caused by 

 catastrophic changes of conditions which occurred within the 

 limited areas to which they were reduced by approaching secular 

 extinctifin. 



(S) The geographical distribution of species within the time- 

 limits of the stages and sub-stages of the geological scale, and 

 consetjuently tliat of the distinguishing types which the species 

 ciinstitute, has been eflected liy natural means. Such means 

 included not only locomotory and mechanical dispersion within 

 those time-limits from one original centre which was then the 

 terminus of an evulutional line, but, at least in the same cases, 

 survival in \arious regions by sejjarate evolutional lines from the 

 faunas of preceding stages and sub-stages was also included. 



(9) The animal and vegetable life of each stage of the 

 geological scale was in the aggregate different as to its forms 

 from that of all others, and each stage and sub-stage was further 

 s|iecially characterised by certain generic, and also more genera!, 

 types or peculiar groups of species. These types, however, 

 were not necessarily confined within absolute time-lim-ts. 



(10) .Although movements and displacements of the earth's 

 crust have from time to time occurred over large portions of its 

 surface, arresting sedimentation or changing its character and 

 causing great destruction of life, there has never been a universal 

 catastrophe of that kind. On the contrary, during all the time 

 that disastrous conditions prevailed in any given area, conditions 

 congenial to the existence and perpetuity of life prevailed in 

 other antl greater areas. 



The second of the two sets of propositions show that certain 

 of the views held by the early geologists, notably those which 

 assumed the universally sharp definition of all the divisions of the 

 geological scale, were radically wrong. .Still, it is evident to every 

 one who is familiar with modern geological literature that those 

 views have continued to exert an adverse influence upon the 

 biological branch of geological investigation long after they have 

 been formally rejected, even by those who continued to be in- 

 fluenced by them. The early geologists adopted methods of 

 investigation which were consistent with their biological views, 

 but it has been shown that from the present standpoint of 

 biology certain of those views were so fiindamentally wrong 

 that the melhoils which were based upon them are quite 

 out of place in modern investigation. Still, those methods 

 ol our energetic predecessors have come down to the 

 present time with such force and with such evidence of the 

 general correctness of the scale which they had established 

 by them, that it has been difficult for their successors to adopt the 

 modification of methods which has been necessitated by the 

 great subsequent revolution in biological thought and methods of 

 investigation. 



The facts which have been stated show that, while the 

 scale which the early geologists established is a wonderful 

 production of human reasoning and the best possible general 

 standard which can be adopted before a comparatively 

 lull in\estigation of the geology of the whole earth has been 

 made, it is not, and cannot be except in a general way, 

 of univers;il applicaliility. That is, while the respective stages 

 and sub-stages of the scale are recognisalile only by means of 

 (heir characteristic fossil remains, it has been shown that any of 

 tho.sc characteristic forms are so liable to range from one stage 

 or sub-stage to another, that it is impossible to sharply define the 

 limits of stages, and often impossible to distinguish sub-stages in 

 <me part of the world as they are known in another ]>art. 



( To be iontinued. ) 



SCIENTIFIC SERIALS. 

 Ihillctm (/<• r Academic des Sciences de St. Pt'tersbotirg, V« 

 serie, t. ii. No. 2, Febmary 1895.— We notice in the proceed- 

 mj;sof the meetings, that the full account of Baron Toll's observ- 

 ations in the New Siberia Islands will soon be published by the 

 Academy. In the meantime the explorer has visited Switzerland 

 m or<ler to study glacier ice, and has found there further proofs, 

 su|iported by .\. Korel, in favour of the masses of ice which he 

 hits found in New Siberia (buried under clays containing fos.sil 

 slenis of Alniis friilicosa fifteen feet long), really being remains 



NO. I 34 I, VOL, 52] 



of the ice-sheet which covered the islands during the glacial 



period. — The yearly report of the Academy, which contains; 

 among other matters, the obituaries of L. Schrenck, A. Midden- 

 dorff', I. Schmalhausen, and I*. Tschebychefi', whom the 

 Academy has lost during the last year. — The positions of 140 

 stars of the star cluster 20 Vulpeculae, according to measurements 

 taken from photographic plates, by A. Uonner and O. Backlund 

 (in C'.erman). The measurements were taken on two plates, one 

 of which had been exposed for twenty minutes only, and the 

 other for one hour, and the accord between the two is most 

 satisfactory, the average difi'erence being o'oos. in right ascen- 

 sion, and o"'02 in declination, while the difi'erence between the 

 measurements on the photographic plates, and the direct measure- 

 ments of Schultz, attains on the average -o-040s. in R.A. and 

 .-o"-55in D. — (Jn the difl'erential equation (/j'/o'.i- = i + R (.»■)/;', 

 by N. Sonin. — On a new entoptric phenomenon, by S. Chirieff. 

 — Note on the last mathematic conversation with P. L. Tsche- 

 bychefi', about his rule for finding the approximate length of a 

 cord, and the means of extending the method to curves of double 

 flexure (all three in Russian). — The ephemeride of the planet 

 (loS) Hecuba, by .\. Kondratiefli'. 



Vol. ii. No. 3, March 1895. — Yearly reports of the Philological 

 Section of the .\cademy, and of the committees : for the Baer 

 l^remium, which was awarded this year to the Tomsk Professor 

 Dogel, for his researches into the histology of the nervous sys- 

 tem, and to Prof Danilevsky for researches into the comparative 

 study of parasites in blood, and the Lomonosov premium, which 

 was awarded to .\. Kaminsky for his work on the yearly march 

 and geographical distribution of moisture in the Russian empirfe 

 in 1871-90. — On the Perseids observed in Russia in 1894 (in 

 French), by Th. Bredikhine. The observations were made by 

 several observers at (Odessa and at Kieff. It must be remarked 

 that the observers have had difficulty in ob.serving the meteors, 

 the course of which made a sharp angle with the direction of the 

 vertical line; and this circumstance is probably not without some 

 influence upon the determination of the radiant point. The 

 meteors observed on July 24, 26, and 27, seem to belong to 

 a meteoric stream other than the Perseids. Combining the 

 results of this year's observations (which are given in full 

 in thirteen tables) with the observations of the precedint; 

 year, and calculating the elements for each of the radiants, 

 the author sees in them a confirmation of the theoretical 

 results he arrived at in his paper on the Perseids of 1893 ! 

 the values of the inclination \i) of the centres of radiation — 

 with the exception of the three first, which are .somewhat un- 

 certain — are all below the value of i for the comet of 1 866. The 

 average value of / before the epoch (.August lO'j) is 60", while 

 after that time it is only 56' ; but this decrease cannot be con- 

 sidered as quite real, on account of the said uncertainty in i for 

 July 24-27. -An inspection of the charts shows that a condensa- 

 tion of the radiation is taking place towards the epoch which 

 falls on the night of the loth to the nth, as seen from the obser- 

 vations made in Italy by P. Denza. The arithmetical average 

 of the coordinates of the three chief radiants of August 10 

 are = 48° 48', and 8 = 56" 30', we have : /=6y 32', ('' = 36'' 51', 

 2'=64°'8, .r = 72°-8, and 1'= +^^''-j,. The value of / corresponds 

 to the radiant of the comet of 1866. Considerable variations 

 appear in the elements n and ir ; the perihelium is displaced in 

 the direction of the orbital motion of the meteors. In a sub- 

 sequent memoir the author proposes to take tip the theory of the 

 subject, and to evaluate the secular variations of the generating 

 orbit of the comet, and of some of its derived orbits. — On the 

 best means of representing a surface of re\"olution on a plane, a 

 mathematical treatment of the subject, in Russian, by A. \. 

 Markoff. — On the limit values of integrals, by the same. — List 

 of the works of P. L. Tschebychefi'. — On the methods for cor- 

 rectly determining the absolute inclination by means of the 

 induction inclinator, and the degree of exactitude lately ob- 

 tained with this instrument at the Pavlovsk Observatory, by II. 

 Wild (in French). The non-periodical variations in the quantity 

 of precipitation at St. Petersburg, by K. Heintz (in Russian, 

 summary in French). — Kjihemeride of the planet (209) Didon, 

 by Mine. Eugenie Maximofi'. — Determinaticm of the magnitudes 

 of the stars in the star cluster 20 \'ulpecuUe, by Mmc. Marie 

 Sliilow. The diameters were measured by the micrometer, and 

 the corresponding magnitudes were calculated by means of 

 Charlier's formula. — On one sum, a mathematical note, (in 

 Russian), by I. Ivanoff. 



The numbers of the loiirnal of Botany for May to July 

 contain, besides mere technical papers, one on the genu 



