178 RED ROT OF SUGARCANE. 



of prolonging the life of the race in Protozoa, bred from a single 

 individual and not permitted to conjugate ; when asexual pro- 

 pagation only is allowed and the environment kept constant, the 

 race soon degenerates and dies out,' 



It is not unlikely, therefore that, there are two types of relative 

 immunity, a genetic, such as is shown by the thin canes so widely 

 cultivated in India, and a fluctuating, and that the latter is much 

 more exposed to the influence of external conditions than the former. 

 Indian thick canes, which have been subjected to vegetative propa- 

 gation without a break for many generations, seem to show no 

 evidence of genetic immunity. Hence frequent change of climate, 

 good cultivation and good hygienic conditions generally, seem to 

 be of great importance in preserving them from epidemics of disease. 



The possession, by India, of a large range of relatively immune 

 (to red rot) thin canes, of hardy habit and great tillering powers, 

 though less productive than the thick canes of other countries, 

 may prove an asset of the greatest value. The growth of seedling 

 canes has been recently undertaken at the Coimbatore cane-breeding 

 station under the control of Dr. Barber. If it is found possible by 

 hybridization to combine the resistance of some of the thin canes to 

 red rot, with the yielding qualities of a thick cane, a great step foi- 

 ward in enabling India to grow enough sugar for her own consinnp- 

 tion and perhaps even to compete successfully with the sugar 

 exporting countries, will have been taken. It is a happy augury 

 that amongst the best of the canes now grown in Java (the most 

 formidable competitor in sugar production that India has to meet) 

 are the progeny of crosses between an Indian thin cane, the 

 " Chunnee " obtained from Shahjahanpui- (where. Dr. Barber 

 informs us, it is locally called Chin), and the Cheribon thick cane 

 grown in Java. 



PUSA, 



June SOth, 1913. 



' Since this was written a very illuminating discussion of the deterioration of 

 sugarcane varieties after long-continued vegetative propagation, written by Harrison, Stock- 

 dale and Waid (West Indian Bulletin, XIII, 1913, p. 177), has been received. 



