•94 



NATURE 



[July 2, 1896 



ambition of modem laboratories, and one which cannot 

 be too strongly impressed on young workers. 



The author's treatment of that most important subject 

 of protoplasmic fusion is not entirely satisfactory. He 

 distinguishes two kinds : (i) fusion in which several cells 

 unite to form a multinucleated mass, as in the Mycetozoa 

 and some RJiizopoda ; (2) conjugation, in which two or 

 more cells fuse to form one cell ; the distinction being 

 that while in the latter case the process is accompanied 

 by nuclear fusion, in the former it is not. In the first 

 place it must be noted that conjugation does not always 

 result in the formation of one cell from two, e.g. many 

 ciliate infusoria ; and in the second, that it is by no 

 means certain that nuclear fusion does not occur between 

 the nuclei of the multinucleated masses resulting from 

 fusion. Moreover the author falls into the common 

 error, found even in some of the best text-books, of 

 calling conjugation a mode of reproduction. On p. 416 he 

 says, '"J'arrive maintenant a une mode spdcial de repro- 

 duction, cellulaire que nous connaissons dej^, a celui que 

 nous avons design^ sous le nom de conjugaiso?i et que 

 nous avons distingue de Xz. fusion" It is perhaps hardly 

 necessary to point out that by reproduction the number 

 of individuals of a species is increased, while by conjuga- 

 tion it is generally diminished. It is true that conjugation 

 results in the formation of a new individuality, but not in 

 the increase in the number of individuals. 



It is hardly going too far to say that conjugation is the 

 opposite of reproduction. It is curious that this mistake 

 should so often be made, and it is most important to call 

 attention to it ; for the confusion between the two pro- 

 cesses, which has no doubt resulted from their accidental 

 association in sexual reproduction, has considerably 

 interfered with the proper appreciation of that most 

 mysterious and important of vital processes — fusion of 

 nuclei and protoplasm. 



With regard to technical terms, we may be allowed to 

 call attention to our author's use of the word Cytodiercsis. 

 He proposes this word for the process of cellular division, 

 which is accompanied by those characteristic transforma- 

 tions of the nucleus which are ordinarily termed karyo- 

 kinetic, reserving the word division for those cases in 

 which the nucleus divides directly. We do not inquire 

 whether such a word is required, but we desire to point 

 out that on the very next page (296), our author uses the 

 word Cytodieresis as the equivalent of Caryodicrcsis (in- 

 direct nuclear division). He says : '■'■Division indirecie 

 (of the nucleus) = karyokinesis (Schleicher) = cyto- 

 dieresis (Henneguy) = mitosis (Flemming)." The loose- 

 ness of thought implied by this confusion in the use of 

 his own word is unsatisfactory, and would by some 

 biologists be pointed to as an example of the result of too 

 strongly holding to a theory which does not conform with 

 all the facts. 



In criticising Weismann's suggestion that the Pro- 

 tozoa are immortal, he says that "a Protozoon which 

 divides dies in the sense which we attach to the death 

 of the higher animals, i.e. that its individuality dis- 

 appears.'' Though we are quite willing to admit that 

 Weismann's statement was more of the nature of a 

 gallery phrase designed to catch the ear of the readers of 

 the modern magazine article, than a serious contribution 

 to science, and that it conveyed no new idea or suggestion, 

 NO. 1392, VOL. 54] 



we cannot follow M. Henneguy in his criticism quoted 

 above. For do not the higher animals also undergo 

 numerous successive divisions in the production of their 

 reproductive cells, which differ in no essential particular 

 from the successive binary fissions which a Paramcecium 

 passes through in its life-history. The only difference 

 which can be pointed to is one merely of degree ; for 

 there is no more an absolute similarity between the two 

 products of fission in an infusorian than there is between 

 the products of the fission (ovum or spermatozoon and 

 parent) which is continually taking place in the higher 

 animals. You might just as reasonably assert that a hen 

 dies whenever it lays an egg, as make the statement that 

 a Paramcecium dies at each process of fission. With the 

 words death and individual a philosopher can do much ; 

 but it behoves practical men to keep a sharp look-out on 

 the use made of those convenient terms. 



The book is well printed and illustrated ; and though it 

 is not a complete and carefully elaborated treatise on pro- 

 toplasm, as the author himself is the first to admit, yet it 

 constitutes a valuable addition to the biologist's library, 

 and cannot fail to be of great use to the teacher as well 

 as to the student. 



A ROMANTIC NATURALIST. 

 From North Pole to Equator, Studies of Wild Life and 

 Scenes in many Lands. By the Naturalist-Traveller, 

 Alfred Edmund Brehm. Translated from the German 

 by Margaret R. Thomson. Edited by J. .'\rthur 

 Thomson, M.A., F.R.S.E. (London : Blackie and 

 .Son, Ltd., 1896.) 



BETWEEN North Pole and Equator " might have 

 been a less attractive, but would have been a more 

 accurate title for this book, for .Siberia and northern 

 Norway are not as far north as the Pole, nor are Nubia 

 and the Blue Nile as far south as the Equator. Between 

 these limits, however, the late Dr. A. E. Brehm made 

 extensive journeys, visiting most of the principal types of 

 country that may be found therein, and studying the 

 characteristic faunas with the enthusiasm of a born 

 naturalist. His great "Thicrleben" is a rich repository 

 of information on the habits of animals, the various 

 groups of which are taken in zoological order. The 

 present book appears to be intended as a supplement to 

 this ; for it is geographical in arrangement, and consists 

 of a series of graphic sketches of wild life in many lands. 



The work opens with a brief homage to the author by 

 his son, and then an admirable introductory essay by 

 the editor upon the work of naturalist- travellers in 

 general, and of A. E. Brehm in particular. Mr. Thomson 

 gives a list of works by English naturalist-travellers, in 

 which we notice Fred Burnaby's " Ride to Khiva," 

 although such books as Lamont's " With the Sea Horses," 

 Butler's " Great Lone Land," and Whymper's " Travels 

 among the ."Xndes of the Equator," arc not mentioned. 



Mr. Thomson classifies naturalist-travellers into five 

 groups — the Romantic (including Sir John de Maundeville 

 and other medieval story-tellers) ; the Encyclopaedists of 

 the sixteenth and seventeenth centuries ; the Genera! 

 Naturalists, ranging from Ray to Humboldt : the 

 Specialist Type — the naturalists of the naval expeditions 



