LkAKE and ram PRASAD. 61 



forms. Balls,* as noted above, has drawn attention to the mixed 

 nature of the cotton crop in Egypt, while the history of the origin 

 of the named varieties of American cottons as far as this is known, 

 sufficiently indicates that in America, too, a similar condition is to be 

 found.f Such a mixed crop no doubt adjusts itself to its surround- 

 ings and, under certain constant conditions, will maintain a definite 

 proportion between the various constituents and even in certain 

 cases, appear to be pure. When such a crop is grown under dif- 

 ferent conditions it is highly improbable that the proportion between 

 the various constituents will remain unaltered. The new condi- 

 tions will favour one or other of the component types which will, 

 in a short time, become the dominant element of the crop. It will 

 not be inappropriate here to refer to the example afforded by wheat. 

 There have from time to time been recorded frequent instances 

 of the conversion of red, to white, wheat and of bearded to beardless 

 as the result of ' degeneration ' consequent on change of environ- 

 ment. Such cases, when put to the test, are invariably found to 

 be referable to the occurrence of an, at first, inappreciable admix- 

 ture of the ' degenerate ' form which, when grown under favourable 

 conditions, increases rapidly and may even ultimately swamp the 

 original kind. If such cases are possible with wheats, in which in 

 Europe, where such instances of ' degeneration ' have been recorded, 

 cross-fertilisation is of the rarest occurrence, the danger of this 

 ' degeneration ' occurring in a crop hke cotton in which cross- 

 fertilisation has also to be taken into consideration must be far from 

 inappreciable. Instances have been actually recorded in the case 

 of maize and the true explanation of such phenomena with 

 especial reference to these two instances is given by De Vries| 

 with much directness. Under these circumstances it appears 

 possible to carry out experiments on the effect of change or 

 environment with pure cultures only, and preferably, with single 

 plant cultures, if such be obtainable. Unless this precaution is 



* Year-book Khed. Agr. Socy., 100r>. 



t The Cotton Plant, U. S. Dept. of Agr., Exp. Sta., Bull. 33. 



i Die Mutations Theorie 1 s. 10, p. 67. 



