May 13, 1897] 



NATURE 



27 



of fossils by one who has thoroughly studied them, and 

 can boldly write down his views. 



The memoir will, doubtless, be severely criticised ; but 

 it is a notable piece of work, and one which all zoologists 

 may read with advantage. 



The first part of Richard Hertwig's memoir, on the 

 development of the unfertilised egg of the sea-urchin, 

 deals almost entirely with the phenomena of nuclear 

 structure and division, and the influence upon them of 

 strychnine and other reagents. The second part of 

 "General Considerations" is an elaborate and exceed- 

 ingly clever essay on nuclear structure and sexual 

 differentiation. 



One of the most important conclusions arrived at, is 

 that the centrosome is a body derived from the nucleus, 

 which passes into the protoplasm of the cell in order to 

 bring into more intimate connection the nucleoplasm 

 and cytoplasm during the process of cell-division. 



He points out that, in such cases as Actinosphierium 

 and other Protozoa, and in the formation of the polar 

 bodies of Asteracanthion, where centrosomes are not 

 apparent, there is very slight connection between nuclear 

 division and division of the surrounding protoplasm. 



The argument is not convincing, and, as Farmer has 

 recently shown, must be considerably strengthened from 

 the botanical side, at least, before the theory can be 

 accepted. 



G. von Koch's essay, on the skeleton of the stony 

 corals, is important and interesting ; but it will not attract 

 so much attention as it might have done, had not Miss 

 Ogilvie's memoir, recently published by the Royal 

 Society, been more elaborate and, many will think, 

 better. 



Of the memoirs dealing with the anatomy and develop- 

 ment of Vertebrata, the one by Hubrecht, on the de- 

 velopment of Tarsius, is the most noteworthy. Although 

 the essay is compressed into only thirty pages, and 

 illustrated by but one plate and fifteen figures in the 

 text, it may be regarded as a summary of the most 

 important results of this distinguished embryologist's 

 work. 



It is quite certain that the peculiar features of the 

 early development and placentation of the Spectral 

 Lemur could have been rightly interpreted only by 

 one who had worked previously at such mammals as 

 the Insectivora. The extremely important resemblance 

 which the Tarsius embryo at a certain stage presents to 

 the human embryo, at what is probably a corresponding 

 stage, is pointed out by Prof. Hubrecht, and the general 

 features are illustrated by a plate of interesting and 

 instructive diagrammatic figures. 



But the memoir is not only strictly embryological; it 

 d^als with the zoological position of Tarsius from other 

 points of view, and the conclusions are arrived at, firstly, 

 that Tarsius is, as regards its dentition, intermediate 

 between the Primates and the Mesozoic Insectivora, 

 and secondly, that Cope's genus Anaptomorphus is 

 intermediate between Tarsius and Man. 



Of the other memoirs on Vertebrata, two seem to 

 stand out prominently as of more than usual interest and 

 importance. These are the essay, by Klaatsch, on the 

 application ofGegenbaur's famous Archipterygium theory 

 to the question of the origin of the pentadactyle limb, 

 NO. 1437, VOL. 56] 



and Rosenberg's memoir on the vertebral column of 

 Mynnecophaga jiibata. 



The former places before the student a clearly-expressed 

 and carefully-considered theory, and is illustrated by 

 numerous really admirable figures. Rosenberg describes 

 some variations he has met with in the vertebral column 

 of Myrmecophaga, and discusses fully the vexed question 

 of the homologies of the Vertebric in the Mammalia. 



Other contributions to this work have been made by 

 Boas, Oscar Hertwig, Corning, von DavidoflF, Solger, van 

 Bemmelen, Scott, Seydel, Maurer and Goppert ; and it is 

 not faint praise to say that they are well worthy of a 

 place in these volumes. 



Since the above was written, the third volume of this 

 gigantic "Festschrift" has been forwarded to us. It 

 is even larger and more profusely illustrated than the 

 first two volumes, and is entirely devoted to questions of 

 vertebrate anatomy. Four of the seven memoirs are con- 

 cerned with the cranial and spinal nerves. Goronowitsch 

 confines his attention to the Trigemino-facialis complex 

 of Lota, and Haller to the Vagus group of the bony fish, 

 the two essays taking the modest share of one hundred 

 pages. 



Unfortunately, perhaps, G. Ruge, who writes on the 

 facial nerve of vertebrates, and Fiirbringer on the spino- 

 occipital nerves of the cartilaginous fish, have been 

 unable to confine their contributions within these limits. 

 To attempt to criticise the 600 pages which they take, 

 would mean an attempt to criticise an encyclopaedia of 

 vertebrate knowledge. The student, however, will find 

 in them a mass of solid facts which have important bear- 

 ings on many important questions that are much dis- 

 cussed in these days. Fiirbringer's memoir in particular, 

 although overpowering in its size, has many passages 

 which summarise, in a clear and masterly manner, ques- 

 tions of the homologies of nerves, and in this respect, at 

 any rate, will form a most useful work of reference for 

 anatomists. 



Of the remaining three monographs the most im- 

 portant appears to be the one by Semon, on the excretory 

 system of the Myxinoids. As in the earlier works of this 

 distinguished anatomist, the reconstruction figures he 

 gives are admirable. 



Max Weber's interesting essay on the brain weight 

 of Mammals, and Leche's researches on the teeth of 

 recent and fossil Lemurs, are important contributions to 

 knowledge ; and although much shorter than others in 

 this volume, are not the less valuable indices of the 

 character of the work that has been produced by the 

 pupils of Carl Gegenbaur. 



THE DREARY DESERT OF NORTH THiET. 



Works of the Tibet Expedition of the Years 1889- 1890, 

 under M. V. Pyevtsoff; Part iii. 4to, pp. 127 ; with 

 six maps. Published by the Russian Geographical 

 Society. (Russian.) (St. Petersburg, 1896.) 



THIS third part of the excellent publication issued by 

 the Russian Geographical Society, contains the 

 records of the incursions of Roborovsky and Kozloft'into 

 the border-ridges of the great Tibet plateau. While the 

 main body of the expedition followed the northern foot 

 of the Astyn-tagh border-ridge (or the " Russian Moun- 



