161 



find in this volume an ample storehouse of examples and sugges- 

 tions. In the absence of any adequate agricultural facilities, 

 the author has carried through an immense amount of laboratory 

 work and now makes a memorable contribution to his subject. 

 The general factor?, and especially the effects of light, heat and 

 moisture in different stages of growth, receive detailed treatment 

 and many significant relations are revealed. 



To criticize the work because of a lack of agricultural con- 

 clusions would be entirely unfair, for the author shows everywhere 

 a notable caution in claiming practical applications. If anything 

 is to be criticized it is the methods that were followed in the 

 breeding work, but even on this ground criticism would hardly 

 be just, for the reason that these particular methods have had 

 the highest approval in the scientific world during the period of 

 Mr. Balls's work in Egypt. 



Perhaps the most direct claim to definite results secured by 

 the MendeHan methods of breeding is on page 119, which gives 

 an account of the breeding of a short-styled variety, in order to 

 lessen the danger of cross- pollination. Short-styled hybrids were 

 secured by crossing the Egyptian cotton with American Uplands, 

 and one of the hybrid strains is described as breeding true for 

 five generations. But the undertaking was abandoned on 

 account of the large number of "rogues" that continued to 

 appear. The Mendelian inferences were preserved by ascribing 

 the rogues to crossing, although the proportion of variants was 

 higher than appeared in other experiments with natural crossing 

 or even with artificial mixing of pollen. The conclusion was 

 drawn that "the accessibility of the style [doubtless meaning 

 stigma] is a minor factor in natural crossing, under the conditions 

 of our breeding plot." 



Nevertheless, this experiment seems to have led to a more care- 

 ful study of the problem of natural crossing or "vicinism" as it 

 is called, in which several interesting points were developed. 

 That some of the results of crossing are greatly at variance with 

 those that have come from similar experiments with Egyptian 

 crosses in the United States, only makes them the more interest- 

 ing as indications of unsuspected influences of external conditions 



