1922.] 



Notices of Books. 



1053 



Part II consists in the main of the systematic classification, the cataloguing, 

 of all the kinds of wheat upon which the author could lay hand. They came 

 to him from every part of Europe, from India, from Persia, from America, 

 from Japan, from Australia, from nearly every quarter in which wheat grows, 

 and are marshalled into groups and sub-groups according to their varying 

 characteristics. Botanists who do this kind of work are a quarrelsome set 

 and the three new " races " (sub-groups) that the author has added to his 

 catalogue of wheats will stir up contention. Some of the world's wheat 

 tracts, Mesopotamia for example, are still imperfectly known to botanists, 

 and their exploration may make yet another re-sorting of the catalogue 

 necessary, but those whose interest is non-critical and lies in the strange 

 multiplicity of the world's wheats may here regale themselves with descriptions 

 and excellent photographs. 



Into the last hundred pages is compressed the matter that, for practical 

 purposes, is the most important of all. There is a chapter on " variation " 

 wherein " sport " forms of wheat are described and a brief explanation is given 

 of the use of " statistical methods," the checks which serve to show whether 

 the numbers and measurements obtained in experiments are or are not likely 

 to be misleading. The professional statistician may here raise his complaining- 

 voice, for the author has, all through, omitted to test, in this way, the numbers 

 and measurements which he has so abundantly furnished. 



Nowadays most of our wheats are " hybrids," and Professor Percival gives 

 a survey of the laws of inheritance which have been disclosed by the breeding- 

 of hybrids and an account of some strange " mongrels" out of wheat crossed 

 on to barley or onto rye. Pessimism runs through the chapter on " Improve- 

 ment and Breeding of Wheat." Mendel's discovery receives its tribute but 

 we read, " most of the characters whose inheritance has been clearly established 

 are of no economic importance "... " the grain-yielding capacity of 

 the plant . . . either does not Mendelise or is at present beyond Mendelian 

 analysis . . . " In so saying, the author displays the caution which an 

 exceedingly difficult problem necessitates, but the omission of what has 

 been done in this important direction is regrettable. 



Very appropriately, a chapter on " Yield " concludes the text. Yields in 

 the different countries of the world, yields in ancient times, the influences of 

 manuring, cultivation, large and small seed, high and low seed rate — all these 

 are briefly reviewed. Perhaps wisely, the author scarcely hints at an attempt 

 to analyse "yielding power" — to specify the features of the different wheat 

 varieties that make them heavy or poor yielders. He might usefully have 

 trod firmer ground, however, by describing how to "test" yielding-power 

 accurately. A bumper crop one year on an experimental plot or even on a 

 field is not sufficient to stamp a " variety " as an exceptionally high yielder r 

 and accurate methods of testing yielding-power are to-day almost pre-eminently 

 important in crop-work. 



The diseases of the wheat plant and their treatment constitute a great 

 subject on which admirable and successful work has been done. An account 

 of this would have enhanced the value of the monograph, but perhaps it 

 ought to be considered beyond its scope. Technical readers may, indeed, be 

 constrained to feel that not one but a series of monographs from more than 

 one pen is necessary to present all that is known about the wheat plant. 



