June i6, iqio] 



NA TURE 



455 



that the greatest of all geographers were sailors, and 

 we venture to adduce the names of Magellan, Colum- 

 bus, Drake, Baffin, Davis, Hudson, Cook, Franklin, 

 Ross, and McClintock in support of it, not to mention 

 any names of those now living. Once more we 

 demur to the use, in any literal sense, of such meta- 

 phorical expressions as "'early Persian Department 

 for geographical intelligence." The early Persian 

 expeditions that we know anything about — namely, 

 those against Greece — relied on spies and on guides 

 picked up at the moment. Finally, where so much 

 is said about Greeks and Alexander one is disappointed 

 to find the famous Macedonian pike (sarissa) dis- 

 guised as ■■ sarina " ; and ballistae and cata- 

 jeltae (did Macedonians use the Roman ballista?) 

 •janslated as "mounted infantn,- and artiller}" " ; 

 uid Nearchus appearing now (correctly enough 

 for those who like that fashion) as N'earkhos, and 

 nov.- (to suit no fashion) as Nearkos. In the case of 

 a name like Nearchus, the free and easy fashion 

 approved by Mr. Tony Weller is hardly to be com- 

 mended. These things are blemishes which we should 

 not care to remark if the book were not so good and 

 so fresh in its essentials. 



GEXERAL BIOLOGY. 



iUgemeine Biologic. By Oscar Hertwig. Dritte 

 Aut!age. Pp. xviii + 728. (Jena: Gustav Fischer, 

 1909.) Price 16 marks. 



IX the review of the second edition of this work, 

 which appeared in this journal in 1906, it was 

 X)inted out that for any single man to undertake to 

 jive a circumstantial and critical account of the 

 lumerous problems of modern biolog\-, and to support 

 lie conclusions arrived at by a sufficient record of 

 lie facts on which they are founded, is too stupendous 

 I task, and one which certainly cannot be adequately 

 juried out in a single volume. The third edition of 

 Dr. Oscar Hertwig's book follows soon after the 

 second, and it is to be inferred that it has been use- 

 ul to a large circle of readers in Germany and else- 

 where, though it has not attracted so much attention 

 n England. It is doubtful whether the third edition 

 vill be more successful in this countn," than its pre- 

 lecessor. It is enlarged by the addition of eighty 

 )ages, and the illustrations in the text, which are 

 fell chosen and for the most part admirably 

 xecuted, have been increased in number from 371 

 3435- 



Dr. Hertwig is a lucid writer, and has a style 

 vhich attracts the reader and carries him easily 

 hrough many difficult places, but in almost ever\' 

 hapter he leaves a certain sense of disappointment. 

 fliere is a vast amount of information, and the argu- 

 aent is clear, and in many places convincing, but 

 he detail is insufficiently worked out. This, perhaps, 

 3 no great fault in a text-book, if such information 

 •s is given is founded on the best and most recent 

 .uthorities, and the references to literature are suffi- 

 iently full and up-to-date. But it cannot be said 

 hat this is always the case. To take some examples, 

 NO. 2120, VOL. 83] 



the author informs us in the preface that the sections 

 on the maturation divisions of the germ-cells, on 

 natural and artificial parthenogenesis, on hybridism 

 and the biogenetic law, have been largely re-written 

 and revised in this edition. 



In the section on the maturation divisions we are 

 disappointed in finding that the discussion turns 

 mainh' on the phenomena observed in Ascaris. The 

 work of vom Rath, Riickert, and Korschelt is also 

 dealt with, but there is no mention of Farmer and 

 Moore's important papers on the Maiotic phase in 

 animals and plants, and their papers, which surely 

 are old enough to be incorporated in a text-book 

 published in 1909, are not even quoted in the list of 

 literature. The section on natural and artificial 

 parthenogenesis is more satisfactory, as a fair sum- 

 mar}' is given of the more important experimental 

 researches on this subject up to the year 1908. The 

 discussion of the results is, however, somewhat un- 

 convincing. 



Mendel's law, which was ignored in the second 

 edition, is concisely dealt with in the latter half of 

 chapter xiii. Here only a few simple cases are quoted 

 to illustrate Mendelian principles, and no discussion of 

 more complicated and unconformable cases is 

 attempted. As in many other parts of the book, the 

 experiments of Continental authors are quoted, but 

 the large amount of English work on the subject is 

 not taken into account. 



Dr. Hertwig is quick to take advantage of the 

 results of Mendelian work in support of his own 

 theories of inheritance, but it is not always easy to 

 understand in this connection, as in many others, 

 what his real opinion is. It might be described, in 

 Mendelian terms, as a polyhybrid of several theories 

 promulgated by different authors ; and sometimes one 

 is inclined to think that, under stress of argument, his 

 system resolves itself, by a process of segregation, 

 into its original elements. He maintains, as he was 

 one of the first to assert, that the chromosomes are 

 the bearers of the heritable qualities of the organism, 

 and it may be said in this connection that he disposes 

 too easily of the evidence furnished by Crampton, 

 E. B. Wilson, and others, that specific organ-forming 

 materials are located in the cytoplasm of the egg. 

 But while admitting the existence of a nuclear idio- 

 plasm, he will have nothing to do with Weismann's 

 theory of biophors and determinants, but holds with 

 Nageli that the idioplasm has a micellar structure, 

 and that it is distributed equally to every product of 

 cell-division. None the less, he speaks of particles 

 (Teilchen) which are bearers of inheritable qualities, 

 and comments on the fact that Mendelian experiments 

 show that these particles must be mobile and capable 

 of forming new combinations. Hence, he says, it is 

 clear that the chromosomes cannot retain their in- 

 dividuality, but must be regarded as tactical combina- 

 tions of smaller units. Few will be disposed to 

 quarrel with this conclusion, but it is not obvious 

 wherein these "smaller units," capable of entering 

 into ■ tactical combinations, and representative of the 

 specific or racial characters (Merkmale) of the adults, 

 differ from Weismann's determinants. 



