- 12 - 



„its attack to a neighbouring individual. The straits to 

 „ which a parasite in conséquence is put to continue its 

 „ existence, and the varied means by which this is effected, 

 „form one of the raost fascinating subjects of biological 

 „study. But the net resuit is that under natural con- 

 ditions the parasite is kept in check. 



„When any crop is grown on a large scale it is ob- 

 „vious that the conditions are changed. A parasite 

 „having by accident fastened on an individual plant in 

 ; ,a plantation and done its fatal work, can then extend, 

 „usually with little difficulty, to contiguous plants. 

 „ Under such circumstances the sprnad of a fungoid 

 „disease can only be compared to a conflagration, which 

 „beginning on a small scale may increase to disastrous 

 „ dimensions. Such troubles are part of the price which 

 „man has to pay for disturbing the order of nature. 

 „The only way to treat them is to endeavour either to 

 „ restore the natural checks which man has abolished, 

 „or, as this can from the circumstances of the case ra- 

 „rely be done, to substitute artificial ones in their place. 

 „And as a matter of practice, by an attentive study of 

 „the habits of the parasite, this can generally be effected 

 „and the injury it inflicts circumvented." 



Si nous ajoutons encore certaines remarques corcernant 

 les causes fondamentales ou accessoires qui, d'ordinaire, 

 président à l'apparition des maladies chez les plantes^ 

 nous pourrons alors entrer dans le détail de la question 

 et décrire les quelques maladies que nous avons obser- 

 vées chez les plantes cultivées à Java pour leur caout- 

 chouc. 



Je ne veux pas m'arrêter ici sur les diverses méthodes 

 de culture qu'on a préconisées et qui jouent un grand 

 rôle dans l'extension des maladies, parasitaires ou autres; 

 chacun sait ce dont il doit tenir compte pour établir ses 



