May 10, 1888] 



NATURE 



27 



Jackson does not appear to favour their claims to rank 

 among the higher group. The vexed question of the 

 homologies of the Arthropod appendages is treated fully 

 The antennules of Crustacea are doubtfully classed as 

 true appendages, while the Crustacean antennae, with the 

 chelicene of Arachnida are regarded as post-oral ap- 

 pendages which have become pre-oral by shifting for- 

 wards. The antennae of Myriapodsand Insects are ruled 

 out, " as being apparently processes of the procephalic 

 lobes ; " while the suggestion that the telson represents a 

 region rather than a somite will meet with very general 

 approval. 



Brauer's classification of Insects is adopted, with some 

 slight modifications, and is given in considerable detail- 

 The leeches are treated with caution as an isolated 

 group, and no suggestion is made of their possible 

 affinities with Turbellaria. 



Among the lower groups the Ccelenterata are dealt 

 with very thoroughly. The possibility of near kinship 

 between the Acraspedote Medusas and the Anthozoa that 

 has found favour of late with Gotte and others is men- 

 tioned, but rejected. The Protozoa also receive very 

 liberal and thorough treatment, more than a hundred 

 pages being devoted to them. As regards classification 

 three main divisions are adopted : the Acinetaria, Ciliata 

 and Mastigophora are classed together as Plegepoda, a 

 group equivalent to the Stomatophorous Corticata of 

 Lankester, and for which the old term Infusoria might 

 conveniently be used. The remaining divisions are the 

 Endoparasita or Sporozoa, and the Rhizopoda, the latter 

 group being equivalent to Lankester's Gymnomyxa. 



Mr. Jackson is a singularly modest writer, and seldom 

 allows his own hand to be seen ; a note on the blood- 

 vessels of the earthworm, in which he questions the 

 existence of the so-called subintestinal vessel, is of con- 

 siderable interest ; and throughout the volume there is 

 abundant evidence of intimate practical acquaintance 

 with the groups he describes so well. 



The importance, even for the junior student, of direct 

 reference to original papers was, as we have noticed 

 above, one of the points on which Prof. Rolleston insisted 

 most strongly. In this respect Mr. Jackson has afforded 

 assistance of a singularly efficient character. Possessed 

 of a most unusually accurate and extensive acquaintance 

 with the zoological literature of all countries, Mr. Jackson 

 has given the full benefit of his knowledge to readers of 

 his book. Every page teems with evidence of the most 

 diligent research amongst authorities, and none but a 

 specialist in each group can estimate rightly the enormous 

 amount of labour that its preparation must have cost him. 

 Only less admirable is the restraint which has enabled 

 him to refrain from burdening the book with an undue 

 number of references, while those that are given have 

 been selected with the utmost care, and arranged in such 

 way as to afford the student aid of a kind hitherto denied 

 him. " The method I have adopted," says Mr. Jackson, 

 "is to citethemost important and recent authorities, which 

 when consulted, will in most cases give the names of all 

 other accounts worth reading, so as to form a really very 

 complete index to the state of present knowledge." It is 

 this "index" which constitutes the characteristic feature 

 of the new edition ; and in the care and thoroughness 

 with which he has compiled it, Mr. Jackson has conferred 



an inestimable boon on zoologists, and has rendered his 

 work indispensable to teachers and students alike. 



The earlier edition of "Forms of Animal Life" was 

 marked by a certain singularity, at times almost gro- 

 tesqueness, of diction, which interfered to some extent 

 with the popularity of the book ; we are glad to observe 

 that care has been taken to remove this blemish, though 

 an occasional tendency to reversion may be noticed in 

 such statements as that "the anterior prostate is divaric- 

 able into two lobes," or that a given figure is " one-half 

 less than natural size." 



It would be better, too, if zoologists could completely 

 emancipate themselves from the traditions of human 

 anatomy, and cease to speak of the anterior part of a 

 rabbit as the "upper half," or to use such terms as 

 " vena cava descendens." " Uro-genital," too, which 

 threatens to establish itself permanently, should not be 

 used for urino-genital ; and the term " pseud-haemal " is 

 objectionable, and, as applied to the vascular system of 

 an earthworm, meaningless. 



However, these are but small points ; and in concluding 

 we acknowledge in the fullest degree the singularly pains- 

 taking and conscientious manner in which Mr. Jackson 

 has fulfilled his task, and the signal service he has thereby 

 rendered to zoologists. "Forms of Animal Life" is a 

 unique book ; none but Prof. Rolleston could have written 

 it ; and probably there is no one who could have retained 

 and developed more successfully than Mr. Jackson has 

 done the exactness and thoroughness to which Prof. 

 Huxley long ago alluded as its special charm. 



A M. M. 



THE CARDINAL NUMBERS. 

 The Cardinal Numbers, with an Introductory Chapter on 

 Numbers Generally. By Manley Hopkins. London : 

 Sampson Low, 1887.) 



UNLIKE Hudibras, who could, as we are told, " extract 

 numbers out of matter," Mr. Hopkins proposes in 

 the essay before us to extract matter from numbers, or, as 

 he says in the preface, " to show that every-day things — 

 numbers being one of them— possess in themselves 

 materials worth investigation, and connections with other 

 subjects of thought and study." Our author does not 

 attempt any systematic investigation of the properties 

 of numbers : to do so would far transcend the modest 

 limits to which he confines himself. He prefers to con- 

 sider numbers in their relation to such subjects as religion, 

 music, poetry, mythology, and superstition. Some purely 

 numerical facts are, however, given, which either are, or 

 else ought to be, found in every text-book of arithmetic — 

 for instance, the rules (given on p. 75, at the beginning of 

 the appendix) for determining when a number is divisible 

 by any of the first twelve numbers, 7 only excepted. The 

 cardinal numbers from 1 to 10 inclusive are treated 

 separately in ten' distinct chapters. These, with the 

 introductory chapter and an appendix, the principal 

 portion of which is taken up with magic squares, form the 

 whole of the work. 



The nature of our author's remarks will be best seen 

 by making a few quotations. Thus ia the chapter on 

 Number tne, after speaking of the unity of the Godhead 

 and the oneness of self, he goes on to say :— 



