Febei 



1903.] 



KNOWLEDGE, 



galapagoensig) by the late Dr. G. Baur. It is a member of 

 the so-called saddle-backed group, of which four species 

 are uow known, namely, T. (jnlnimji'ieiinl^ from Charles 

 Island, T. ej^hijqtiiiiH from Duucan Island, T. becki from 

 North Albemarle, and T. ahingdotd from Abingdon. In 

 one of his two papers Mr. Rothschild describes, under the 

 name of T. wallacei, a shell probably from Chatham Island, 

 Galapagos group, which was formerly in Bullock's Museum. 

 The author believes it to be the only known representative 

 of a once common species. We hojse shortly to publish 

 an article on giant tortoises. 



A correspondent " Adolescens," writes to us as follows: — 

 " I have read that some kinds of bees, flies, and water- 

 fleas, are produced from eggs that have never been 

 fertilised by the male. Is this true ? I shall be obliged 

 if you will kindly answer this question in the ' Notes and 

 Queries ' of your next issue, and tell me what animals 

 are produced (if any) by parthenogenesis." We can 

 perhaps answer this best by quoting from Dr. D. Sharp, 

 who writes as follows iu the hrst of the two volumes on 

 Insects in the Camhridfje Natural History : — 



" There are undoubted cases in insects of the occurrence 

 of parthenogenesis, that is, the production of young 

 without concurrence of a male. This phenomenon is 

 usually limited to a small number of generations, as in 

 the case of the Aphididm (plant-lice), or even to a single 

 generation, as occurs in the alternation of generations of 

 many Cynipodn' (gall-flies), a jiarthenogeuetic alternating 

 with a sexual generation. There are, however, a few cases 

 of insects of which no male is known (iu Tenthredinidie, 

 Gynipidw, Coccidm), and these must be looked upon as 

 perpetually parthenogeuetic. It is a curious fact that the 

 result of parthenogenesis in some species is the production 

 of only one sex, which in some insects is female, in others 

 male. ... In some forms of parthenogenesis, the yoimg 

 are produced alive instead of in the form of eggs." It 

 may be added that at least some drone bees are produced 

 by parthenogenesis. 



•» 



j^oticts of Boofts. 



"A Naturalist in Imuan Sk.vs." By A. Aloock, m.b., 

 i.L.i)., F.R.s. (Murray. U)02.) 18s. — The author tells us in his 

 preface that this volume "is compiled from the records of the 

 Royal Indian Survey Ship 'Investigator' " ; but the compila- 

 tion has been made with such rare skill and judgment that the 

 past lives again in his pages, and the distant is brought near. 

 Hence, we ventnre to think this book will come to many as a 

 revelation, not only of the methods of marine surveying and 

 zoological investigation, but also of a world of life, kaleido- 

 scopic in its changes, and romantic in its facts. He has conjured 

 up a panorama of the most alluring description ; Indian temples 

 and tropical islands, coral reefs and peaceful lagoons, raging 

 seas, and the mysteries of their uttermost depths, are each in 

 turn presented, and their several inhabitants pointed out and 

 described, in such a way that wo see them, not as so many 

 ethnological and zoological examples, but as living creatures, 

 leading strenuous lives hitherto undreamt of by the sta3--at- 

 home reader — unless he be also a zoologist. If none of the facts 

 in this book are absolutely new it is because they liave already 

 been ]iublished by the author, and others working out the 

 materials supplied by him, in tlie pages of the I'mceeiiini/x 

 of various learned societies. Here, however, they were acces- 

 sible only to the professed zoologist ; in their present form, 

 carefully selected and reset, they will bo welcomed by the 

 lover of travel and natural history the world over. Of the 

 many remarkable facts recorded in this book not the least 

 interesting arc those concerning certain viviparous rays, the 

 young of which are nourished by a secretion, formed by vascular 

 filaments of the oviduct, closely analogous to milk. These 

 filaments, in a small sting-ray (Tri/gnn lilti-Leri) were found 

 "dri])])ing with milk.'' This is conveyed into the body of the 

 embryo, not through the mouth but directly into the throat 

 through the modified first pair of gill-clefts or spiracles ; the 



milk-secreting filaments passing from the wall of the oviduct 

 into these apertures. The method of extracting the milk by 

 sucking, whichprevails among the higher mammals, is here of 

 course impossible, consequently, it is pumped into the gullet by 

 the contraction of muscular fibres investing the filaments in 

 question, a method which recalls the s(j«i^ing pi^essof feeding 

 which obtains among the mavsupials.' The al>SS»tion of the 

 yolk-sac by the short-tailed hat^Ay (l'ter)ff^t}iifiifiici-ura) is 

 another extremely interesting i^slaiK^, al%^3spg an instructive 

 illustration of the substitiuJou^^f .or^ns.^"- This yolk-sac 

 '• contained no blood-ves^is fpf^absc^jgyig thej^mk such as are 

 generally found in alh^ofe.sacs "^"gSt^nste^ this work was 

 done by the externat K-anchial .gij&ment^=^i^e long and delicate 

 vascular processes which .later!form t^fi^ternal giUs, and which 

 later still disappear and a*e replace^^ the internal gills of the 

 adult. Of the weird anjiSW^der^- ways of the deep-sea fi.shes 

 and other creatures, ^j^-how'ttoy contrive to make life possible, 

 if not worth living, m thc^e regions of eternal night and 

 unbroken silence, Dr. Alcock has much to say, and not a little 

 that is new. Dr. Alcock is inclined to doubt the authenticity 

 of the accounts of the tree-climbing powers of the celebrated 

 robbor-crab {Birtjus lah-o) which he found in South Sentinel 

 Island. That these stories are probably true, however, we may 

 infer from the accounts published not long since by Dr. 

 Andrews, of the British Museum. On Christmas Island he 

 found these crabs climbing the sago-palms when the fruit was 

 ripe in order to feed thereon. .Apparently, some successfully 

 made the ascent, whilst others waited below to feast upon the 

 fruit which had either fallen naturally or had been detached by 

 their fellows up aloft. Musical crabs, fighting crabs wielding 

 ponderous war-clubs, hermit crabs which live in bamboo stalks, 

 and numerous other remarkable Crustacea are vividly described 

 in these pages, together with a host of other creatures, the 

 mere enumeration of which would unduly prolong this notice. 

 Reluctantly we bring this short account to a close, with the 

 conviction that the book will take first rank among those of its 

 kind — and these are many. It is a delightful volume, well 

 printed, well illustrated, handsomely bound, and without a dull 

 page- 



" Biological Laboratory Methods." By P. H. Mell, ph.d.. 

 Director of Alabama Experiment Station, &c. (MacmiUan &' 

 Co.) — This book combines general instructions for the use of 

 the microscope and its accessory apparatus, directions for 

 imbedding, staining and generally preparing micro-sections, with 

 separate chapters on photo-micrographic apparatus and methods, 

 the study of bacteriology, and the polarisation of light, and 

 concludes with useful formuke and tables, together with 

 suggestions for the arrangement of the laboratory and its 

 furniture. The hints generally for conducting laboratory work, 

 although suffering from the defect of superficiaHty, which must 

 of necessity occur where so large an area is covered in a small 

 volume, are concise and in many respects valuable. 



The aim of the writer, set forth in the '• Introduction," to 

 I' deal with facts in a perfectly scientific, accurate manner," 

 is unfortunately unrealised in many of the chapters, and 

 especially is this so when he is dealing with microscopical 

 and general optical principles. The writer assumes, for 

 instance, that a Coddington Magnifier is an Aplanatic Triplet, 

 and further states that the Wollaston Doublet increases the 

 distance between the lens and the object, where.as the reverse is 

 .actually the case. The descriptions of spherical and chromatic 

 aberration are both vague and confusing. He states that the 

 method of correcting spherical aberration is to so grind the lens 

 that its curvature at the edge is less than at the centre, pre- 

 sumably referring to a system of " figuring " which is never 

 applied to microscopic objectives : while an acliromatic objective 

 is stated to be ' so constructed that the coloured rays decomposed 

 out of the white light by the first lens are recomposed by the 

 next lens into white light." 



The instructions for the working of the Abbe Condenser, 

 evidently the only condenser known to the author, are va^ue ia 

 description and wrong iu practice, the worker being recom- 

 mended to " stop down " and to control the light by racking it 

 out of focus --a method which was in vogue twenty years 

 ago, when the necessity of focussing the condenser, and the 

 advantages generally derivable from its use, were little appre- 

 ciated. Ho further states that •' dark ground illumination is 

 obtained by adapting a diaphragm with the opening in the 

 shape of a ring and the centre oblique." 



