JANTJAKY 8, 1915] 



SCIENCE 



69 



If notliing more, they point out a promising 

 method of detecting and measuring associa- 

 tional preferences among animals wliicli may 

 be readily trapped. 



The evolutionary theories of Darwin and 

 Wallace were largely founded upon personal 

 observations of geographical distribution. The 

 modern student of genetics, on the contrary, 

 carries on his studies for the most part in the 

 laboratory and the breeding pen. It is signif- 

 icant, therefore, that Bateson,^ perhaps the 

 foremost living Mendelian, devotes a consider- 

 able portion of a recent volume to the prob- 

 lems of geographic variation. And one can 

 hardly read that volume attentively without 

 being convinced that the field naturalist holds 

 the key to some of the most important secrets 

 of nature. It is not improbable, therefore, that 

 works of the sort here reviewed will come to 

 receive more serious consideration from those 

 who are concerned primarily with the problems 

 of organic evolution. 



Feancis B. Sumner 



ScBipps Institution por 



BlOLOeiCAL Eeseaech, 

 La Jolla, Calif. 



Chemical Technology and Analysis of Oils, 



Fats and Waxes. By Dr. J. Lewkowitsoh. 



Edited by George H. Warburton. Vol. II. 



1914. Pp. 994. $6.50. 



The first volume of this work appeared in 

 this country while the author lay dead. While 

 the death of an eminent chemist is always 

 to be regretted, in this case there was an addi- 

 tional reason for regret — the delay, or worse 

 yet, the possible non-appearance of the re- 

 mainder of the treatise. The delay has been 

 so slight as not to be noticed and the editorial 

 work has been most satisfactorily performed by 

 Mr. Warburton, who for seventeen years was 

 associated with Dr. Lewkowitsch in his analyt- 

 ical practise. 



This volume has been increased in size by 

 thirteen per cent.; important additions have 

 been made in the articles on linseed, tung, 

 soy bean, cocoanut oils and candelilla wax, as 



3 Op. cit. 



well as minor additions to other portions to 

 bring them thoroughly up to date. 



The work may fairly be described as monu- 

 mental; nothing would seem to have escaped 

 attention. Even the toxicity of the different 

 chlorides with two atoms of carbon has been 

 given, as having a bearing on their technolog- 

 ical uses. 



Notwithstanding the very full table of con- 

 tents, the reviewer misses, and must wait a 

 year perhaps for, an index which it would 

 seem advisable to include in each volume. 

 Similarly the reviewer is inclined to question 

 the advisability of including the large amount 

 of statistical matter about the commercial 

 side. That, it would seem, might well form 

 the subject of a single volume, like the 

 author's "Laboratory Guide to the Fat and 

 Oil Industry " and be revised and brought up 

 to date more frequently. If the work con- 

 tinues to grow as it has in the past, it would 

 seem worth while to consider its publication 

 by some society, as its compeer "Beilstein" 

 has been taken over by the German Chemical 

 Society. A. H. Gill 



SPECIAL ASTICLES 

 THE NITROGEN NUTRITION OP GREEN PLANTS 



It is the teaching of botanists that green 

 plants obtain their nitrogen chiefly in the form 

 of nitrates, though ammonium salts may be 

 utilized to some extent by certain plants at 

 least. Exceptions to this general rule are 

 those plants provided with root-tubercles (and 

 bog plants and others which have mycorrhiza?). 

 These plants obtain their nitrogen in the form 

 of organic compounds made for them by the 

 bacteria growing in the tubercles. 



That nitrogen circulates throughout the 

 structures of plants in organic combination 

 is certain. There does not appear to be any 

 reason why similar compounds which are solu- 

 ble and diffusible (amino acids?) should not 

 be taken up through the roots of plants and 

 utilized as such. It appears to the writer that 

 this must very probably be the case. Argu- 

 ments in favor of this view are: 



1. The nitrogen nutrition of the leguminous 



