316 NATURAL CROSS-FERTILIZATION IN INDIA. 



this lie great possibilities of improvement by mere systematic 

 selection as well as the explanation of the extraordinary deteriora- 

 tion, noted below of Egyptian cotton grown from unselected seed. 

 It is in fact clear that where a valuable variety grows in close prox- 

 imity to a worthless one of the same main type, great care, in the 

 following year, in the selection of parents for seed production, is 

 necessary if the valuable strain is to be kept pure. This, agreeing 

 with experience in America where (pp. 131 and 132 of the Yearbook 

 of the U. S. A. Agricultural De'partm.enf, 1903) it is advised that 

 seed fields of valuable cotton should be located ' half a mile or 

 more from any other cotton,' should be taken into account in seed- 

 growing in the future.'* 



Natural crossing in cotton has been observed in other countries. 

 In Egypt, Balls' considers that the amount of cross-feitilization 

 which takes place in the Egyptian cotton fields is between five and 

 fifteen per cent, per annum ard the accumulated eiiect of this 

 annual crossing maintains the crop as a mass of natural hybrids. 

 It is not surprising therefore that the introduction of Egyptian 

 cotton seed into Texas has given rise to difficulties which can be 

 entirely explained by the occurrence of natural crossing both 

 previous to and subsequent to the introduction of this crop into 

 America. The American experience, which is no doubt typical, is 

 summed up by Cook^ in several papers which are of great 

 interest to workers on cotton in India. 



5. Linseed. 

 The information on the subject of the modes of pollination of 

 the cultivated forms of linseed {Linum, usitatissimum, L.), has been 

 summed up recently by Fruwirth,^ who states that as a general 

 rule self-pollination is the rule and that good setting is obtained 

 under bag without loss of vigour. While he does not appear to 



1 Balls, Jovrnal of AgrieuUnnd Science, Vol, II, 1908, p. 378, 



2 Cook, Bulletins lot! & 157, Bureau of Plant Tndvsfru, V. S. Dejxnfnienf of Agricnltuyc, 



1909. 



S Fruwirtli, Die Zitchtvng Jer landw. Rulti(rfan:en, Bd. Ill, 1906, s. 45. 



