526 



SCIENCE, 



[Vol. V., No. 125. 



ness in details is as clearly apparent in every 

 one of the sharp and terse definitions. These 

 present the few characteristics which apply to 

 the whole group, and only that group, rarely 

 extend beyond three lines, and are expressed 

 in words as well chosen as the characteristics 

 themselves. As the student follows them from 

 type to family, he sees clearly that the animal 

 kingdom is really a cosmos, not the chaos 

 which is presented in too many of our zoologies. 

 Under each type, class, and order, each or- 

 ganic sj'stem, the embryonic development, and 

 the habits of the group are described in the 

 same clear, brief terms. Thus one can study 

 the fourteen hundred pages of the ' Grundziige,' 

 or the eight hundred of the ' Lehrbuch,' and 

 scarcely erase five words to a page, or con- 

 dense in any way the sentences, without en- 

 tirely changing their meaning. How many 

 thorns would be removed from the path of 

 the working zoologist if all our writers could 

 borrow Professor Claus's sharpness of vision, 

 and accuracy of description ! 



The general part of the work covers a hun- 

 dred and eighty pages. Of these, a hundred 

 and thirty are devoted to the general qualities 

 of protoplasm, the structure and development 

 of cells and tissues, the general anatomy and 

 physiology of each w compound organ,' and 

 embryonic development. The next fifty pages 

 contain in brief outline the history of the 

 science, and the discussion of the theory of 

 evolution. This is, unlike most zoologies, 

 perhaps the most interesting and striking por- 

 tion of the book, especially as in this part the 

 genius of the author, in the choice and arrange- 

 ment of material, is the plainer because of the 

 greater liberty here possible. As specially 

 interesting, might be noticed the author's views 

 of parthenogenesis (p. 106) as a reproduc- 

 tion, on the part of agamic females by true 

 eggs, "by no means to be relegated to the 

 category of germ-cells," — views quite op- 

 posed to the quotations from English writers 

 so common in our American literature, although 

 Professor Claus seemed to be supported by 

 Balfour and a majority of the German school. 



Under Protozoa in the special part, the 

 Monera are disregarded as a separate group, 

 and merged with Rhizopoda and Flagellata. 

 Thus neither nucleus nor pulsating vesicle is 

 considered a necessary characteristic of Rhizo- 

 poda. The Flagellata are pro vision all}' classed 

 under the Infusoria, with expressed doubts of 

 their animal character. Among the Flagellata 

 are reckoned the Astasiadae (Euglena) and 

 the Volvocinidae, although the close alliance 

 of the latter family to the Algae is clearly 



acknowledged. In an appendix to the Pro- 

 tozoa, the Bacteria and Gregarinidae are briefly 

 considered. It is an open question whether 

 this is an improvement on the arrangement of 

 forms in the ' Grundziige,' where Bacteria, 

 Flagellata, Myxomycetes, Catallacta, and 

 Labyrinthuleae are all discussed in connection 

 with Protozoa, but as groups of very doubtful 

 position and affinities. 



The study of the Coelenterata is introduced 

 by a description of the three individual types, 

 polyp, medusa, and ctenophore. The dis- 

 cussion of their resemblances and differences 

 brings the different forms of this group clearly 

 before the student at the outset, beside fur- 

 nishing him a basis for their classification. 

 The sponges are considered as merely a sub- 

 group of Coelenterata. 



On account of its embrj'onic development, 

 Balanoglossus is assigned to an appendix at 

 the end of the echinoderms. 



Under Vermes the Nemertini are still re- 

 tained with the Platyhelminthes. The Gephy- 

 rea are placed between the Chaetopoda and 

 Hirudinea as the second sub-class of Annelida, 

 while the Rotatoria form the fourth and last 

 class of Vermes. This is certainly an ex- 

 tremely practical classification, even though 

 some might prefer to consider the Rotatoria 

 earlier in the series of worm-forms, on account 

 of their general affinities. 



The second volume contains, 1°, Mollusca ; 

 2°, Molluscoidea, to which are reckoned only 

 Polyzoa and Brachiopoda as possessing strong 

 affinities to annelids as well as Mollusca ; 3°, 

 Tunicata ; and, 4°, Vertebrata. Thus over five 

 hundred pages of the two volumes are devoted 

 to Invertebrata. The seven hundred figures 

 are well chosen, and far above the average in 

 beauty and clearness. Under every type and 

 class are references to the latest and best 

 literature on the subject. The translator has 

 had a difficult task. It is no easy matter to 

 translate into idiomatic English the author's 

 condensed and pregnant sentences, where every 

 word is important. A few cases might be 

 noticed where the rendering of single words 

 might be improved ; but, as far as can be 

 judged from a careful comparison of about 

 thirty pages taken at random through the 

 work, even such cases are rare, and in general 

 the translation certainly gives a very just ren- 

 dering of the author's ideas. 



The publishers have given us a good page 

 and paper, and clear type. Altogether, it is 

 the only realty satisfactoiy manual which we 

 have in English, and one which no teacher or 

 student of zoology can afford not to possess. 



