256 



SYMBIOSIS 



symbiotic forbearance is exhibited by Bletilla and its fungal 

 partners : 



La plante, au cours de sa periode de vegetation active, differencie ses 

 principaux organes sans avoir a subir 1'action des champignons. Elle 

 est soumise a cette action seulement a partir du debut de la seconde periode, 

 pendant un temps difficile a limiter exactement mais qui ne doit pas depasser 

 six mois. C'est pendant ce temps qu'elle forme son rhizome et qu'elle 

 murit ses fruits. 



Here, then, the " infection " sets in only at " harvest-time/' 

 The fungi, in their turn, are " assujettis a un regime analogue,'' 

 and this so much so as to find themselves " empeches d'accroitre 

 d'une facon continue leur pouvoir d'action sur leur hote." 



Prof. Bernard, by the way, seems to attach too little importance 

 to the fact that the orchids belong to the Monocotyledons, the 

 class of flowering plants in which the embryo of the seed has only 

 a single cotyledon or seed-leaf, and which class seems to be marked 

 by a " congenital ' ' weakness as regards root-development . Thus , 

 though in their earlier stages Palms develop a radicle or tap-root, 

 no British representatives of the class do so ; nor, with the one 

 exception of the Butcher's Broom, do they form woody stems. 

 Monocotyledons have generally bunches of fibrous roots : their 

 stems are often bulbs or corms, and are not commonly much 

 branched. But if the Monocotyledons are backward in the 

 most important matter of root-development, they are certain to 

 be correspondingly backward in the matters of " capitalisation " 

 and of " export," and generally thus to present a comparatively 

 inferior " trade-balance." They cannot vie with the more 

 strenuous Dicotyledons for the most complete fare, and for the 

 choicest biological services. Though they be but relatively 

 backward, this is enough to involve liability to disease in view 

 of the eternal antagonism between the good and the (relatively) 

 bad, and inasmuch as health and status are to a large extent 

 determined by socio-physiological factors. We must be on our 

 guard, therefore, lest we make any and every monocotyledonous 

 development the measure of normal and primary development 

 amongst plants generally. This is how Prof. Bernard, on p. 43, 

 refers to the class-character of the orchids : 



Chez les Monocotyledones en general, les graines mures ont un albumen 

 et un embryon normalement differencie ; il devait en etre ainsi chez les 

 ancetres des Orchidees. Mais chez la plupart des representants actuels 

 de cette famille, 1'albumen disparait de tres bonne heure dans la jeune 

 graine, ou ne s'y forme pas du tout ; 1'embryon reste indifferencie, sans 



