28 



-\ . / rURE 



[May 9, 1895 



nine families of Bombyccs. ending with the Psycliida; is 

 written in the same careful and painstaking manner as its 

 predecessor. The first volume has been well received 

 abroad, but the foreign critics regret the absence of refer- 

 ences, a deficiency more felt by them than by British Icpi- 

 dopterists. The foreign critics speak of the plates as a 

 veritable storehouse of remarkable varieties : but we must 

 again comment very se\erely on the action of the 

 publishers in issuing two editions of the work, one with, 

 and the other without illustrations, without any reference 

 to the illustrated edition in the letterpress of the other, so 

 far as we have noticed ; and in the case of the second 

 volume, without even as much as an advertisement to 

 call attention to its existence. 



There are several points of general scientific interest 

 suggested by an examination of Mr. Barrett's book. .A 

 great number of species recorded as British by the older 

 entomologists, but rejected by Doubleday and .Stainton, 

 have latterly been rediscovered and reinstated. This has 

 happened so often, that it seems likely that when we 

 eliminate accidentally introduced species (chiefly North 

 .American), and European species wrongly determined, 

 it will be found that the information given by the older 

 writers was far more accurate than the writers of the 

 middle of the century were at all disposed to admit. Nor 

 did the latter allow for the diflficulty of communication 

 with the continent at the beginning of the century, which 

 added much to the improbability of specimens asserted 

 to have been taken in England, having been simply 

 brought over from the continent. 



In estimating the probability of a reputed species being 

 truly British, the chief factor to be taken into account is 

 its continental range. It is evident that the British 

 fauna is slowly changing, some specimens becoming rarer 

 or even disappearing, and others becoming commoner, or 

 establishing themselves in England for the first time. 

 There is also some tendency in Mediterranean species to 

 extend their range further north in Western Europe. As 

 the late Mr. Stainton once remarked, the comparison of 

 our present lists with those of the future, will be likely 

 to yield highly unexpected and interesting results. 



\V. F. K. 



Qtielknkunde. Lchre r'on dcr fiildung und 7'o?n Vor- 

 kommcn dcr (lucllen und des Grundwiissers. Von 

 Hyppolyt J. Haas. 8vo. pp. 220. Illustrations in the 

 text. (Leipzig : J. J. Weber, 1895.) 



Prof. Haas, of Kiel, when asked to edit and bring up to 

 date the "Qucllcnkunde" of Abbii I'aramelle, came to the 

 conclusion that in order to state the present position of 

 the science of springs and underground water in a satis- 

 factory form, an entirely new work was necessary. Hence 

 the book under notice. In such small compass, nothing ap- 

 proaching a complete treatise could possibly be attempted. 

 The chief features of springs, their classification and rela- 

 tion to geological conditions, arc discussed according to a 

 clearly arranged plan under five principal heads. First 

 comes a discussion of springs in general, including an 

 historical introduction, in illustration of which several of 

 Athanasius Kirchcr's quaint pictures are reproduced. 

 The following sections deal with thermal anel mineral 

 springs, underground water, and the art of finding springs. 

 In the last fli\i-,ion we find some remarks on the divining- 

 rod. The bdfik should prove useful to students of 

 physical geography and to those concerned with the 

 practical utilisation of a water-supply derived from wells. 



.A number of diagrams are reproduced from the works 

 of Daubrce and other authorities. Although several 

 Kn^'lish authors are cited, we fear that I'rof. Haas has not 

 made himself familiar at first hand with the literature of 

 the subject in English, which is by no means meagre in 

 records -of original observations on the movements of 

 underground water, and deserves more recognition than 

 it receives. 



NO. 1 332, vor.. 52] 



LETTERS TO THE EDITOR. 



[TAe Editor dMs not hold himself responsible for opinions ex- 

 pressed hy his correspondents. Aeither ean he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of NATURE. 

 J^o notice is taken of anony/nous communications.'^ 



Uniformitarianism in Geology. 



Dr. -VI-FRKD W.vi.l.ACE, in his Icllcr to N.vri'RK of .May 2, 

 calls attention to the significant l;\cl that catastrophes caused hy 

 volcanoes " may be of greater magnitiule now than in geologic 

 times," owing to the crust of the earlli being lliickcr now than 

 it was then. He, however, is mistaken in supposing that this 

 consideration has been overlooked by geologists, if he will 

 kindly refer (o " Geology," vol. i. p. 449, he will find it there 

 stated, speaking of the oltlcr fissure and explosive eruptions, that 

 " there is nothing to show that this [the cx])losive] action was 

 on the s;ime scale of magnitude and permanence as those o( late 

 Tertiary and recent date. With the greater lliickness of the 

 earth's crust and the greater resistance presented liy its rigidity, 

 volcanic eruptions must with time, as suggested long ago by Elie 

 de Beaumont, have altered with the alterations of those con- 

 ditions, and may now be exhibited under a ])hase very different 

 from those of the earlier ]>eriods." 



Or again, he will find in " The Tosiiion of (leology " (" Col- 

 lected I'apers," p. i.) it slated that, though one form of volcanic 

 action (the fissure) was more active in the past than at present, 

 that " explosive eruptions are more violent now than in former 

 limes." .\nd again, at p. 145 of the same work. I remark that 

 " while with the thinner crust of former times, there would be a 

 more frequent extrusion of the molten rock, there are prolKdily 

 with the thicker crust now formed and con.sec|uenlly its greater 

 resistance, greater forces stored in the explosive eruptions of the 

 present day." 



The instance relied upon by Dr. Wallace is, however, another 

 striking example, if others were needed — though in this case it 

 is on the inverse side as against meteorological agencies — o( the 

 non-uniformity in degree between the action of the forces of jiasi 

 and present times. The increaseil thickness of the crust i-. 

 not, however, the sole cause of the violence of recent eruptions, 

 nor are they, I imagine, due to the presence of occluded water 

 in the volcanic foci. The terrific eruptions of Krakata"b and 

 other volcanoes are, I conceive, due simply lo the access of vast 

 volumes of surface waters and their sudden flashing into steam. 



Volcanic action, therefore, does not seem to me lo he in any 

 way in contradiction lo the conception of uniformity of kind or 

 law, and to non-uniformily on the question of degree. 



Sevenoaks, May 4. ' JoSEl'li I'rf.stwich. 



Green Oysters. 



I HAVi: just received a " Note," extracted from the RTonilore 

 Zoologico Italiano, of Florence, by Dr. Caraz/.i, in which a num- 

 ber of unsupported statements are made as to " phagocvtosis in 

 .Molhisca." 



.\mongst other statements, I find " Non solo sono osscr- 

 vazioni erronee quelle del Lankester, malamente ripeliile 

 dcllo Chatin, ma lo sono egualmenle <|Uelle del I'elseneer e ilel 

 Bniyne." I am surprised that my zoological friends in Florence 

 should publish a bare statement <if this nature «ilh<«it a shred of 

 evidence lo support it. I desire to draw attention lo the sini|)Ie 

 .assertion made by Dr. Cara/zi, and to lei those who are respon- 

 sible know that land others expect him lo show in detail what is 

 the error in ihe observations published by me on the green oysters 

 of Marennes. 



It is certainly not a usual thing for a Society lo allow an author 

 lo print vague .accus;ili(ms of inaccur.acy in reference to other 

 writers, williout the smallest allempi lo justify such accustilions. 



Dr. Carazv.i's .tsserlion is all Ihe more remarkable, since it 

 appears Ihal he has no' examined Ihe true huitres de Marennes 

 at all, and is singularly ill-informed as lo the histology ami 

 physiology of MolUisca. 



I shall be very nnicli surprised if Dr. Carazzi can show that 

 Ihe observations published by me on green oysters in 1SS6 

 Hiuart. fourn. Aficr. Sci. vol. xxvi.) arc erroneous, and sliall ai 

 once re-examine Ihe mailer if he succeeds in throwing doubt on 

 the facts as slale<l by me. 



Inferences from observed facts .stan<l in a different position 

 from the observations themselves. 



I W.1S the firsl lo describe the cells laden with green granules 



