July 3, 19 13] 



NATURE 



447 



The author points out that "the abortion of cer- 

 tain members of a brood or group to the favour 

 of others " is a phenomenon of frequent occur- 

 rence in nature, and he instances those flowers 

 which produce more ovules than ever ripen into 

 seed. According- to his theory, the expulsion of 

 the polar bodies is simply an incident recalling 

 the past history of the race, and the physiological 

 explanations are uncalled for. On this view the 

 remarkable constancy of the phenomenon among 

 the higher animals seems to be insufficiently ac- 

 counted for, while the reduction processes remain 

 imperfectly explained. 



In the second chapter the author deals with the 

 problem of heredity, and comes to the conclusion 

 that at present the facts can only be elucidated by 

 the light of mental, not material, processes. 

 While inclining to the memory theories of Butler 

 and Hering, he expresses himself also as favour- 

 able to an explanation assuming the succession of 

 a series of complex chemical changes after the 

 manner postulated by Delage or by J. T. Cunning- 

 ham in his hormone theory of heredity. In the 

 third chapter the author returns to the subject 

 of brood formation and its relation to ordinary 

 cell-division, and the various types of brood forma- 

 tion are briefly described. Chapter iv. first ap- 

 peared under the title, "The Dual Force of the 

 Dividing Cell," but in this work it has undergone 

 much revision, and is headed "The New Force, 

 Mitokinetism." In addition to the existence of a 

 well-known physical force, and others the physical 

 interpretation of which is uncertain (such as 

 protoplasmic streaming), the author invokes the 

 aid of a new force which he calls "Mitokinetism," 

 besides assuming the existence of further forces 

 which have no clear analogies either in physics or 

 in biology. The whole chapter, though ingenious, 

 is highly speculative, and consequently difficult to 

 criticise in a short review. 



In chapter v. Prof. Hartog returns to the sub- 

 ject of nuclear reduction, which is already touched 

 upon in chapter iii. His view may be summar- 

 ised in the statement that the process is a necessary 

 consequence of cell fusion, instead of a prepara- 

 tion for it. The author appears to us to lay 

 altogether undue stress upon the difference be- 

 tween the two theories. He points out that a 

 reduction must take place somewhere, otherwise the 

 number of chromosomes would go on increasing 

 in geometrical progression. This is, of course, ob- 

 vious, and since the reduction usually (though 

 not invariably) takes place in the last division of 

 gametogenesis, it appears to us legitimate to 

 regard it as a preparation for zygotic union. 



In the next chapter Prof. Hartog reverts to his 

 views on fertilisation. He suggests that owing 

 NO. 2279, VOL. 91I 



to the ambiguity of the term "fertilisation" it 

 had better be replaced by " syngamy " when used 

 in its strict morphological sense as the fusion of 

 two cells or nuclei. He makes the interesting sug- 

 gestion that the formation of the fertilisation mem- 

 brane is the last relic of the time when the newly- 

 formed zygote usually went into a resting con- 

 dition. 



In chapter vii. the author again gives the argu- 

 ments in favour of the theory that acquired charac- 

 ters can be inherited, and in chapter vii. the case 

 against a purely mechanistic interpretation of life is 

 once more stated. Great stress is laid on the vital 

 powers of readjustment and compensation under 

 diverse conditions, and the possession of a spon- 

 taneity which is never possessed by machines, since 

 these work for the mechanician, whereas the living- 

 organism works and adapts itself to its own racial 

 needs. 



The chapter on the biological writings of Samuel 

 Butler is well worthy of perusal, and we feel 

 indebted to Prof. Hartog for giving us a further 

 insight into the fascinating personality of the 

 author of "Erewhon." The last two chapters 

 deal with education problems, and though not with- 

 out interest, seem rather out of place in the present 

 book. Though containing little that is new, the 

 volume supplies a useful summary of the author's 

 views on many subjects, and as such it forms a 

 welcome addition (o the " Progressive Science 

 Series." Francis H. A. Marshall. 



FOUR ZOOLOGICAL TEXT-BOOKS. 



(1) Elementary Biology: Animal win/ Human. By 

 J. E. Peabody and A. E. Hunt. Pp. xiv + 212. 

 New York : The Macmillan Company ; London : 

 Macmillan and Co., Ltd., 1912.) Price -is. 6d. 

 net. 



(2) An Introduction to Zoology. With Directions 

 for Practical Work. (Invertebrates.) By 

 Rosalie Lulham. With Illustrations by V. G. 

 Sheffield. Pp. xv + 457. (London: Macmillan 

 and Co., Ltd., 1913.) Price 75. 6cl. net. 



(3) Teachers' Manual of Biology. By Prof. M. A. 

 Bigelow. Pp. ix+113. (New York: The 

 Macmillan Company ; London : Macmillan and 

 Co., Ltd., 1912.) Price 15. 8rf. net. 



(4) A Manual of Zoology. By Prof. R. Hertwig. 

 Third American from the ninth German edition. 

 Translated and edited by Prof. J. S. Kingsley. 

 Pp. xii+606. (New York: Henry Holt and 

 Co., 1912.) 



(1) ' I "" HE lively book by Messrs. Peabody and 



X Hunt strikes a modern educational note, 



for the primary emphasis is placed on practical 



values. It is intended as a guide to school- 



