128 



NATURE 



[Dec. 17, 1874 



fiei-manent vertebra. The new segmentation, however, 

 does not follow the lines of the earlier division, but passes 

 between the ganglionic and the vertebral portions, in fact, 

 through the middle of each protovertebra. In conse- 

 quence, each spinal ganglion and nerve ceases to form 

 the front portion of the primary vertebra formed out of 

 the same protovertebra as itself, but is attached to the 

 hind part of the permanent vertebra immediately pre- 

 ceding. Similarly, the rudiment of each vertebral arch 

 covering in the neural tube, no longer springs from the 

 hind part of the protovertebra from which it is an out- 

 growth, but forms the front part of the permanent ver- 

 tebra, to which it henceforward belongs By these 



changes this remarkable result is brought about, that 

 each permanent vertebra is formed out of portions of two 

 consecutive protovertebra;." 



Such being the case, the question suggests itself as to 

 what becomes of the portion of the new column corre- 

 sponding to the anterior or cephalic end of the proto- 

 vertebrae nearest the skull which has no other semivertebra 

 wherewith to blend. It has no neural arch, and does not 

 enter into the formation of the cranium, for the proto- 

 vertebra does not enter that complicated structure. We 

 are not informed as to its destination. May it not be that it 

 persists as the odontoid process of the axis, which, from 

 not being able to maintain an independent existence, 

 joins, late as we know, the second cervical vertebra ? This 

 hypothesis involves a difficulty, no doubt, as to the nature 

 of the atlas, but seems to throw some light on the pecu- 

 liarity in the conformation of the axis. 



The development of the vascular system, through the 

 various complex stages, is most fully explained, with the 

 assistance of several very instructive diagrams. We can 

 hardly help having a feeling of regret that the common 

 fowl does not resemble its allies, the Mound-makers 

 {Migapodidce), in having only a single carotid artery 

 instead of two, because then we should have the ques- 

 tion answered as to the method by which the companion 

 vessel is lost, which is at present not in the least under- 

 stood. 



We must refer our readers to the work itself for an 

 account of points so important as the development of the 

 Wolffian bodies and their ducts, the spinal cord, the 

 heart, the nasal pits, as well as the many other details 

 respecting the different organs which go to form the adult 

 bird ; original observations will be found on most ; and 

 where these are absent, the excellence of the rhinni of the 

 work of others will clearly prove with what conscientious 

 care the authors are carrying out the evidently pleasurable 

 labour they have imposed upon themselves. As far as 

 the permanent kidneys are concerned, it must be men- 

 tioned that, from their manner of development, it is 

 shown that their separation morphologically from the 

 Wolffian bodies is an occurrence of purely secondary 

 importance. 



Now that we have a text-book of embryology produced 

 under such favourable auspices, it is to be hoped that the 

 far-spread ignorance on that subject, which is at present 

 but too apparent on all sides, will no longer exist and 

 that a higher standard whereon to commence further 

 investigation will quickly develop itself amongst all 

 English students of biology. 



i A. H. G. 



OUR BOOK SHELF 



A Monograph of the Post-tertiary Entonwsiraca of 

 Scotland. By G. S. Brady, H. W. Crosskey, and D. 

 Robertson. (Palaeontographical Society.) 



In this part of its publications the Pateontographical 

 Society has done good service to that large body of geo- 

 logists who take interest in the story of the old glaciers 

 and icebergs of Britain and love to gather when they can 

 the traces of the life which peopled the frigid sea once 

 spread over some of the richest tracts of our present islands. 

 The descriptions here given of the localities and sections 

 of the glacial deposits are perhaps all that could be at 

 present attempted, but they offer a very puzzling problem 

 to the reader who would fain know something of the 

 chronology of the deposits. Nothing can show more 

 satisfactorily the labour which has in recent years been 

 bestowed upon these Post-tertiary clays than the fact that 

 a few years ago not one of the minuter forms of Crus- 

 tacean life had been noted as occurring in them, while 

 now more than 130 species belonging to twenty-seven 

 genera of Entomostraca have been carefully examined 

 and described by the authors of this Monograph. The 

 names of Brady and Robertson are a sufficient guarantee 

 for the faithfulness of these descriptions, while Mr. Cross- 

 key's [knowledge of the localities and his expertness as 

 a collector have given an additional fulness and value 

 to the Monograph. Though but dry reading for ordinary 

 people, these pages, with their accompanying admirably 

 executed plates, will be a valuable boon to many a student 

 of Post-tertiary geology. 



Tlie Races of Mankind : being a Popular Description of 

 the Characteristics, Manners, and Customs of the 

 Principal Varieties of the Human Family. By Robert 

 Brown, M.A., &c. Vol.11. (London: Cassell,Petter, 

 and Galpin. No date.) 

 This work, which seemed in the first volume to promise 

 some scientific value, is now down to the level of the 

 popular picture-book. There are some good pictures in 

 it, and no doubt the boys and girls who have it given 

 them will pick up ideas from its compiled informa- 

 tion. We have not done more than look into it here and 

 there, finding errors small and great. At p. 4, a Spanish- 

 American is called, with curious felicity of blundering, 

 "Don Jose Marie del Muchos Dolores." At p. 22 we 

 read, " The smallest shopkeeper in Germany expects to 

 be addressed as Mr. Court-Councillor." At p. 284 is a 

 picture of a Bushman playing on the goura, or musical bow. 

 This appears to be an altered copy of the illustration in 

 Mr. J. G. Wood's " Natural History of Man," vol. i. 

 p. 295 ; but whereas Mr. Wood's artist knew that Bush- 

 men have narrow heads, and drew his accordingly, the 

 present draughtsman, by his alteration, has given his 

 native a skull of enormous width. At p. 1 13, in contradic- 

 tion to the weight of ethnological evidence, the Austra- 

 lians and Tasmanians are treated as belonging to the 

 same race. When we add that many of the illustra- 

 tions are taken without acknowledgment from Figuier's 

 " Human Races," it is not necessary to inquire further 

 where M. Figuier got them. 



LETTERS TO THE EDITOR 



[The Editor does not hold liimself responsible for opinions expressed 



by his correspondents. Neither can he undertake to return, 



or to correspond with the writers of, rejected manuscripts. 



No notice is taken of anonymous cojnmunications.'\ 



The Royal Agricultural Society and the Potato Disease 



My main object in writing to you was to correct what Mr. 



Jenkins admits were "grotesque statements," and to claim for a 



distinguished English botanist credit for work done by him thirty 



years ago, which I was unwilling, without protest, to see assigned 



to anyone else. 



