528 MacDougal: Svmiuosis axd Saprophvtism 



adduced In the foregoing paper may be briefly stated as follows : 

 I. The term saprophyte should be applied to those species 

 only which derive their food-supply from organic products, un- 

 aided by chloroph)-lI, and without the intervention of other organ- 

 isms. The true saprophytes therefore include numerous bacteria, 

 fungi and but one seed-forming species— J r///Ar///.?.;^r//^ aphylla. 

 The saproph}-tic capacity of the seedling has been extended to 

 cover periods of varying length in the life of the hemi-saprophytes 

 and with symbiosis has reacted to diminish the tendency to store 

 reserv^e material in seeds. 



r 



IT. The degenerations of the true saprophytes are generally 

 parallel to those of mycorhizal forms. 



Ccph 



9 



Corallorhiza Arbonica are to 



be added to the list of chlorophyllcss plants furnished with stomata. 



IV. The offsets of Calypso are occasionally converted into 

 coralloid mycorhizas as in Aplcctnim. The stele of such structures 

 is not differentiated into xylem and phloem. The occurrence of 

 the coralloid mycorhiza is accompanied by variations in the form 

 of the leaves, and of the decrease in the capacity of the storage 

 organs in the specimens examined. 



V. Corallor/iica Ari-jo)iica exhibits greater development of the 

 symbiotic adaptation than C. Corallorhiza. The stele is quite 

 primitive throughout, chlorophyll isjacking, and stomata are pres- 

 ent on the coralloid branches only. The epidermis of the pre 

 morse rhizome is furnished with hyathodes. The aerial shoot 

 is furnished with large intercellular spaces, but may carry 

 on epidermal transpiration only. The fungus in the coral- 

 loid structures consists of a permanent mycelium, with external 

 and internal branches ; the former are organs of absorption and 

 reproduction, the latter are organs of interchange between the 

 members of the symbiosis. The higher plant affords lodgment 



. for the fungus and carries on chemical transformations the prod- 

 ucts of which are available to the fungus. The latter absorbs 

 and yields to the higher plant in a more or less complex form the 

 products of the humous soil. 



VI. All endotropic mycorhizas do not conform to a single phys- 

 iological type. The theory of Janse that endotropic fungi are 

 negatively chemotropic to oxygen, and bear the same relation to 



