184 



SCIENCE 



N. S. Vol. XXX. No. 762 



author's theory, the better-seeing right eye 

 would determine the use of the right hand 

 (the center for the muscles of which is in the 

 left hemisphere) in preference to the use of 

 the left (the center for the muscles of which 

 is in the right hemisphere). But, now, why 

 should it? The macular region of the right 

 retina is connected with the right hemisphere 

 by just as short and pervious a neurone path, 

 as with the left hemisphere. The associative 

 neurones between the visual and motor centers 

 of the right, are just as short and pervious as 

 those of the left, hemisphere and, for objects 

 situated in front of the infant, the left hand 

 may be used as conveniently as the right. 

 Under these circumstances, in which there are 

 two possible paths with no advantage of one 

 over the other, why should the nerve impulse 

 traverse, as a matter of fact, one chain of 

 neurones rather than the other? In the opin- 

 ion of the reviewer. Dr. Gould's theory fails 

 to answer this question. And it is only by 

 answering this question that any theory of the 

 dependence of motor asymmetry upon sight 

 can hope to succeed. 



H. C. Stevens 

 University of Washington, 

 Seattue, Wash. 



Colloids and the UUramicroscope, A Manual 

 of Colloid Chemistry and Ultramicroscopy. 

 By EiCHARD ZsiGMONDY. Authorized trans- 

 lation by Jerome Alexander. Small 8vo, 

 xii + 245 pages, illustrated. New Tork, 

 John "Wiley and Sons. Cloth, $3.00. 

 The study of colloidal solutions has justly 

 received considerable attention in recent years. 

 The appearance of the German edition of 

 Professor Zsigmondy's book in 1905 was 

 warmly welcomed, for besides being written 

 in the admirable spirit of a careful student, 

 it presented results obtained by means of a 

 new apparatus, the ultramicroscope, which 

 opened up a new method of attack of some of 

 the perplexing problems of solutions. 



The ultramicroscope, the chief feature of 

 which is that by means of a special con- 

 trivance the sun's rays are concentrated so as 

 to produce a very powerful light upon the 



material to be examined under a compound 

 microscope, has enabled investigators to see 

 minute particles hitherto invisible. Thus this 

 instrument is of value not only in studying 

 suspensions and colloidal solutions, but also 

 in investigating all kinds of extremely finely 

 divided material, and so the book is of greater 

 significance than its title would indicate. 

 Indeed, the results that have already been ob- 

 tained by means of the ultramicroscope go far 

 toward strengthening the probability of the 

 atomic and molecular theories of matter. 



The book is especially valuable in that it 

 opens up new avenues of experimental investi- 

 gation, and it is to be hoped that the methods 

 of ultramicroscopy may be still further im- 

 proved in the near future. During the in- 

 terval between the appearance of the original 

 and the translation, additional facts concern- 

 ing colloids have been accumulated by means 

 other than the ultramicroscope ; these have not 

 been considered. But it is to be remembered 

 that the volume does not claim to be an ex- 

 haustive treatise on colloids. 



To most chemists and physicists the work 

 of Siedentopf and Zsigmondy is perhaps al- 

 ready familiar. It is to be hoped that this 

 translation of the latter's book will be read by 

 many others, particularly by those engaged in 

 biology and applied chemistry. The book con- 

 tains two colored plates not in the original, 

 and also some minor additions to the text. 

 The translator has done his work well ; though 

 a less rigid adherence to the letter of the orig- 

 inal would have resulted in better idiomatic 

 English. The book is printed upon good 

 paper, the type used is excellent, and the cloth 

 binding is neat, but the price is rather high. 

 Louis Kahlenberg 



SPECIAL ARTICLES 

 another explanation of the hardiness of 



GRIMM alfalfa 



In the issue of Science for December 18, 

 1908, attention was called to certain points in 

 connection with the history of Grimm alfalfa: 

 in Minnesota. In that article the well-known 

 hardiness of this strain was attributed to ac- 

 climatization, subsequent to its introduction in 



