272 SYMBIOSIS 



upon a misunderstanding of the nature of Symbiosis, and of the 

 laws of biological action and reaction. 



Comme je 1'ai dit des le debut de ce memoire, la realisation de la sym- 

 biose est surtout un effet du hasard ; si les Orchidees ne produisaient 

 pas chaque annee d'innombrables semences, elles seraient vouees bientot 

 a la disparition. La symbiose est une forme exceptionnelle et appar- 

 emment paradoxale de maladie infectieuse, mais qui n'echappe pas cepen- 

 dant au.; lois communes de la pathologic. De meme qu'une premiere 

 atteinte benigne d'une maladie infectieuse accidentelle peut preserver 

 un etre d'une atteinte plus redoutable, de meme 1'infestation par un 

 champignon attenue peut " vacciner " un embryon d' Orchid 6e et prevenir 

 1'infestation par un champignon plus actif. Mais, dans ce cas singulier, 

 1'accoutumance aux parasites est devenue assez parfaite pour rendre la 

 vaccination nefaste ; 1'infestation prolongee, qui entrainerait ailleurs un 

 pronostic grave, permet seule ici le developpement. 



Instead of which it should have been simply shown that we 

 have here to do merely with " un symbiose de luxe," and not 

 with the primary and normal form of Symbiosis so widely and 

 usually exhibited by the strenuous green plant. It should have 

 been pointed out, free from all " pathological " jargon, that the 

 life of the orchids is precarious precisely for the reason that 

 they have placed too much reliance upon a particular form of 

 Symbiosis, which involved comparative neglect of service in 

 Norm-Symbiosis. If it may be said of symbiotic adaptation that 

 it is " paradoxale de maladie infectieuse " this is true in the 

 sense that such adaptation represents the very antidote of 

 disease, the very emblem of health. Much in the same unwarrant- 

 able way in which orchid-cwm-Fungus Symbiosis is here described 

 as belonging, though perhaps somewhat paradoxically, to the 

 region of Pathology, so it has hitherto been customary amongst 

 Biologists to pronounce the case of the lichen as one closely 

 related to Parasitism. Recent research, however, has shown 

 that in the lichens, penetration of the living gonidia by fungal 

 hyphae occurs very seldom, and that a theory of Parasitism based 

 upon its occurrence has very little evidence to support it. The 

 symbiotic nature of the lichen-organism is generally accepted 

 by lichenologists. We have seen that the activity of most lichens 

 is in harmony with the law of Concord, and that they are accord- 

 ingly marked by great usefulness and remarkable longevity and 

 health. If it be that nevertheless the " lois communes de la 

 pathologic " are here applicable, this is for the reason, I believe, 

 that such laws represent mere re-statements of fundamental 





