350 



WILD AND CULTIVATED COTTONS 



Lindau. 



Marshall 

 Ward. 



Mendel- 

 ism. 



the stocks used in the production of the cross. The progeny had, moreover, 

 long pollen-grains, which was thus demonstrated as the dominant condition 

 and such a result would ordinarily be spoken of as an instance of 'reversion.' 

 But the modern school of hybridists accepts it as an axiom that when dis- 

 similar gametes are crossed the resultant is the reappearance of an ancient 

 form. And further, such reversions do not breed true, but, on the contrary, 

 split in the next generation or so into the components of their production. 

 (Cf. with remarks under G. arboreum, var. assamica, p. 111.) 



6. Lindau (Engler and Prantl, rv. 3 B., pp. 274-336) has advanced a classi- 

 fication of the genera of ACANTHACE.S: in which the characteristics of the 

 pollen-grains are accepted as generic and of value in systematic study. 



7. The late Professor H. Marshall Ward, in his fascinating new work on 

 'Trees' (1905, in. 93), says: 'Another curious fact is the co-existence of 

 more than one shape in the same flower. This is well seen in the Black 

 Currant, where the grains may be shaped like a tetragonal pyramid, or cone, 

 truncate or not ; or a four-angled prism, with the faces plane or curved ; or 

 even a globoid or deformed and creased body. No doubt some of such 

 polymorphic grains are imperfect, and the shape varies (as does that of all 

 pollen-grains) according as viewed in dry, or in some water-extracting 

 medium, such as alcohol or glycerine ; but polymorphic pollen-grains are 

 known for many other plants, of which I may mention the Rowan, and 

 are very commonly found of two sizes in different or in the same flowers, e.g. 

 in the Tamarisk.' 



8. Crepin (Bosa Hybridce, Bull. Soc. Boy. de Bot. de Belgique, vol. 33, 

 1894, pp. 8-9) draws attention to the diversity, and imperfectly formed 

 pollen-grains as an almost certain indication of hybridisation. 



Enough has perhaps been said in exemplification of the great 

 diversity of form and size manifested by the cultivated cottons* 

 With other plants the explanation is often accepted without question 

 that such multiplicity and diversity are indicative of complexity in 

 hybridisation. That suggestion is pregnant with interest to the 

 cotton cultivator. The experiments at cotton improvement, hitherto 

 published, have consisted in field selection of accidental appearances, 

 without, in but few instances, the effort having been put forth to test 

 the origin, purity or dominance of the conditions subjected to pro- 

 tracted elimination. 



Mendel (' Exper. in PI. Hyb./ transl. by W. Bateson in ' Jour. 

 Eoy. Hort. Soc. Engl.,' vol. 26, 1901, pp. 1-32) in his historic and 

 epoch-making essay on the hybridisation of the edible pea (Pisum 

 sativum) laid it down that 'those characters which are trans- 

 mitted entirely, or almost unchanged in the hybridisation, and 

 therefore in themselves represent the hybrid characters, are termed 

 the dominant, and those which become latent in the process, 

 recessive.' But by subsequent cultivation Mendel found that the 

 individuals which then manifested the recessive type continued to 



