GENETICS 319 



claimed that the genetic system of the sweet pea is, as things go, fairly 

 well understood. To do any of these things would require a control of 

 events so lawless and rare that for ages they must probably remain 

 classed as accidents. On the other hand, the modes by which combina- 

 tions can be made, and by which new forms can be fixed, are through 

 Mendelian analysis and the recent developments of genetic science now 

 reasonably clear, and with that knowledge much of the breeder's work 

 is greatly simplified. This part of the subject is so well understood 

 that I need scarcely do more than allude to it. 



A simple and interesting example is furnished by the work which 

 Mr. H. M. Leake is carrying out in the case of cotton in India. The 

 cottons of fine quality grown in India are monopodial in habit, and are 

 consequently late in flowering. In the United Provinces a compara- 

 tively early-flowering form is required, as otherwise there is not time 

 for the fruits to ripen. The early varieties are sympodial in habit, and 

 the primary apex does not become a flower. Hitherto no sympodial 

 form with cotton of high quality has existed, but Mr. Leake has now 

 made the combination needed, and has fixed a variety with high-class 

 cotton and the sympodial habit, which is suitable for cultivation in the 

 United Provinces. Until genetic physiology was developed by Men- 

 delian analysis, it is safe to say that a practical achievement of this 

 kind could not have been made with rapidity or certainty. The re- 

 search was planned on broad lines. In the course of it much light was 

 obtained on the genetics of cotton, and features of interest were dis- 

 covered which considerably advance our knowledge of heredity in sev- 

 eral important respects. This work forms an admirable illustration 

 of that simultaneous progress both towards the solution of a complex 

 physiological problem and also towards the successful attainment of an 

 economic object which should be the constant aim of agricultural 

 research. 



Necessarily it follows that such assistance as genetics can at present 

 give is applicable more to the case of plants and animals which can be 

 treated as annuals than to creatures of slower generation. Yet this 

 already is a large area of operations. One of the greatest advances to 

 be claimed for the work is that it should induce raisers of seed crops 

 especially to take more hopeful views of their absolute purification than 

 have hitherto prevailed. It is at present accepted as part of the nat- 

 ural perversity of things that most high-class seed crops must throw 

 " rogues," or that at the best the elimination of these waste plants can 

 only be attained by great labor extended over a vast period of time. 

 Conceivably that view is correct, but no one acquainted with modern 

 genetic science can believe it without most cogent proof. Far more 

 probably we should regard these rogues either as the product of a few 

 definite individuals in the crop, or even as chance impurities brought 



