September io, 19 14] 



NATURE 



31 



m 



hypertonic solution no development takes place. 

 Other hypertonic solutions, provided they possess 

 a similar osmotic action and are not poisonous 

 (as is the case, for instance, with copper salts), 

 may also be used. Better methods have since 

 been devised, e.g. treatment first with a fatty 

 acid, such as butyric, then with sea-water, next 

 with the hypertonic solution and finally removal 

 to sea-water. The fatty acid initiates membrane 

 formation, the hypertonic solution the oxidation 

 processes. Various substances, such as saponin, 

 which have a lytic or solvent action upon the 

 cortical layer of the egg and therefore lead to 

 membrane formation, can also be substituted for 

 fatty acid. 



Another fact of considerable interest is that 

 blood or tissue-extracts, or the dead or living 

 sperm, of a foreign species will induce membrane 

 formation in the unfertilised sea-urchin egg, while 

 the extracts of the sea-urchin itself are inefficient 

 to do so and the living sperm is alone effectual. 

 This appears to be due to the fact that the foreign 

 materials can diffuse into the egg, while its own 

 materials are unable to, but must be can-ied by 

 the living sperm. Various questions connected 

 with heredity are discussed, and finally a chapter 

 deals with the interesting question — can an 

 embryo develop from a sperm? Apparently in 

 yolk and white of egg, fowl sperm can undergo 

 transformation into a nucleus, but we are not yet 

 in a position to state that the sperm can undergo 

 mitosis outside the egg. Altogether this book 

 can be recommended as an authoritative state- 

 ment on artificial parthenogenesis by one who has 

 himself contributed so much to the subject. 



(2) Comparatively simple as the structure of the 

 blood seems at first sight to be, the more it is 

 studied the more complex it becomes, and the 

 literature dealing with this subject has now 

 become truly enormous. In the present volume 

 the author has attempted to summarise the re- 

 searches that have been carried out on the 

 structure, functions, and origin of the various 

 elements of the blood, both normal and abnormal, 

 which make their appearance in cases of disease. 

 On the whole we think the author has accom- 

 plished his object, and has produced a reference 

 book which will be very useful to those who are 

 working at this subject. A biblic^raphy, a 

 glossary of haematological terms (which runs into 

 , more than thirty pages), and indexes to subjects 

 and to authors, complete a work which must have 

 entailed a considerable amount of labour. 



R. T. H. 

 NO. 2341, VOL. 94] 



MATHEMATICAL TEXT-BOOKS. 



(i) (a) Plane and Solid Geometry. By Prof. 

 W. B. Ford and C. Ammerman. Edited by 

 E. R. Hedrick. Pp. ix -!- 32 1 -f xxxiii. (New 

 York : The Macmillan Co. ; London : Mac- 

 millan and Co., Ltd., 1913.) Price 55. 6d. net. 



(b) Solid Geometry. By Prof. W. B. Ford and 

 C. Ammerman. Edited by F. R. Hedrick. 

 Pp. ix + 215— 321 +xlix. (New York: The 

 Macmillan Co. ; London : Macmillan and Co., 

 Ltd., 1913.) Price 35. 6d. net. 



(2) A School Course in Geometry. By VV. J. 

 Dobbs. Pp. xxii + 427. (London: Longmans, 

 Green and Co., 1913.) Price 35. 6d. 



(3) Analytic Geometry and Principles of Algebra. 

 By Prof. A. Ziwet and L. A. Hopkins. Pp. 

 viii + 369. (New York : The Macmillan Co. ; 

 London: Macmillan and Co., Ltd., 1913.) 

 Price 75. net. 



(4) Slide-Rule Notes. By Colonel H. C. Dunlop 

 and C. S. Jackson. Pp. 127. (London : 

 Longmans, Green and Co., 1913-) Price 

 25. 6d. net. 



(5) A First Numerical Trigonometry. By \V. G. 

 Borchardt and the Rev, A. D. Perrott. Pp. xi 

 + 159 + xvii + xvii. (London: G. Bell and 

 Sons, Ltd., 1913.) Price 25. 6d. 



(6) Elementary Graphic Statics. By J. T. W'ght. 

 I Pp. xii + 227. (London: Whittaker and Co., 



191 3.) Price 4s. net. 

 i (7) Models to Illustrate the Foundations of 

 Mathematics. By C. Elliott. Pp. viii + 116. 

 (Edinburgh: Lindsay and Co., 1914.) Price 

 2s. 6d. net. 



(8) Exercises in Mathematics. By D. B. Mair. 

 Pp. xi -r 469. (London : Macmillan and Co. , 

 Ltd., 1914.) Price 45. 6d. 



(9) A School Statics. By G. W. Brewster and 

 C. J. L. Wagstaff. Pp. viii+ 248. (Cam- 

 bridge : Heffer and Sons, Ltd., 1913.) Price 

 35. net. 



(10) Proceedings of the London Mathematical 

 Society. Second series. Vol. xii. Pp. lix-f- 

 488. (London : Francis Hodgson, 1913.) 



(i) T N America, as in England, the teaching of 

 1 geometry has altered recently both in 

 method and scope; and these changes are indi- 

 cated in the report of the committee of the 

 National Education Association, the recommenda- 

 tions of which have been in the main adopted 

 by the authors of this volume. The limitations 

 of the subject-matter are similar to those with 

 which English students are famihar, but there is 

 a marked difference in the arrangement. The 

 treatment of areas is postponed nearly to the 

 end of the course, thus enabling angle and 



