MALADIE ET SYMBIOSE 263 



What are these important consequences ? On the one hand 

 the infected tissue gains considerable importance vis-d-vis to 

 the ensemble of the un-infected tissue of the plant. This Prof. 

 Bernard would interpret as meaning that the respective orchids 

 have to suffer more intensely than others the action of their 

 " commensals." 



He argues from the protracted growth and the persistence 

 of the roots that the plant harbours living fungi during the whole 

 course of its life : 



L'etat de symbiose devient pour elle une condition de vie continue 

 au lieu de n'etre comme chez les Orchidees a poussees sucoessives de 

 racines fugaces, qu'une condition periodique. II est pratiquement facile, 

 par exemple, de trouver en toute saison des racines de Vanda abondamment 

 infestees et d'en extraire des pelotons de mycelium capables de developpe- 

 ment. Cette continuite de 1'infestation temoigne assurement d'une 

 adaptation a la symbiose approchant de la perfection. 



Yet I do not think that Prof. Bernard has fully established 

 the thesis that the Sarcanthineae owe their comparatively high 

 evolution to fungal Symbiosis, which may have been but one 

 component, and a relatively late and minor one, whilst the result 

 was in reality due to the long protracted action of Norm- 

 Symbiosis with all it involved in symbiotic moderation and in 

 the establishment of symbiotic sense. There may have been 

 comparative abstinence from in-feeding or from excessive water- 

 drinking, or other factors may have existed, such as go in support 

 of Norm-Symbiosis, whilst moderating fungal Symbiosis. The 

 presence of fungi per se does not prove that they play everywhere 

 the same part. This follows even from Prof. Bernard's own 

 description of the conditions of " Symbiosis." These particular 

 types of epiphytic orchids may have succeeded better than others 

 in keeping the fungi in their proper place, albeit in close union, 

 whilst treating them even to some considerable symbiotic for- 

 bearance. That is to say that the orchids in this case have been 

 able to make such provision as to accommodate useful servants 

 without the least harm to themselves and to Norm-Symbiosis, 

 and so as to interfere least with progress. On no account can we 

 accept the theory that a " Symbiosis " need only to become 

 " continuous," i.e., attached, in order to be perfect or favourable 

 to progressive evolution. Neither do the fungi really live con- 

 tinuously with the Sarcanthineae ; and Prof. Bernard has to 

 admit that in the case of Phalaenopsis and Vanda : 

 les premieres racines ne s'infestent pas au contact des tissus dn 



