iiAi'. II] GUILDS 



20I 



nay be found growing accidentally in the hollows of old trees ; they 

 iccur however only in places where considerable masses of soil facilitate 

 he development of true subterranean roots, and they cannot in any way be 

 onsidered as epiphytes. 



The varied contrivances by means of which higher epiphytes have 

 jecome adapted to their mode of life are so closely connected with the 

 onditions of existence in rain-forests and arc so characteristic of the latter, 

 hat they and the forests should be discussed together. It may now 

 nerely be stated that they chiefly belong to the ferns and orchids (Fig. i ii), 

 nd in America specially to the Bromeliaceae. 



3. SAPROPHYTES. 



Saprophytes constitute a group of plants that dispense with chlorophyll 

 md are therefore dependent on organic nutriment. They obtain this 

 lutriment from dead vegetable and animal substances, and in a more 

 )r less decomposed condition according to the particular species. 



The vast majority of saprophytes belong to the Bacteria, Myxomycetes, 

 ind Fungi ; the remainder are phanerogams. There are no other classes 

 >f plants represented among them. In accordance with their mode of 

 lutrition, all saprophytes, except perhaps bacteria, must be derived from 

 reen assimilating plants. Among phanerogams, numerous transitions 

 till exist between purely inorganic and purely organic methods of nutrition. 

 The first stage is denoted by the appearance of the mycorhiza, by means 

 f which phanerogams and ferns were first enabled to utilize the organic 

 onstituents of humus. Increasing dependence on the fungus of the 

 iiycorhiza. whose role has been transformed from that of a mere supplier 

 )f nitrogen to that of a universal provider, has led through numerous 

 ntermediate stages to the purely saprophytic mode of life. The sapro- 

 phytic habit has conferred on the plants which possess it the power of 

 )ccupying stations w'here, on account of insufficient illumination, green 

 slants can exist feebly or not at all. Like halophytes and epiph}-tes, 

 saprophytes are also fugitives from the struggle for existence. 



Despite the wide distribution of mycorhiza only a relatively small 

 lumber of phanerogams, belonging to a few families, have adopted the 

 purely saprophytic mode of life. The majority of these are monocotyle- 

 dons and chiefly orchids, but the small family of Burmanniaceae is chiefly 

 saprophytic, and that of Triuridaceae exclusively so. Among dicotyle- 

 donous plants only Gentianaceae and Monotropeae possess saprophytic 

 'Pecies. 



The change in the mode of nutrition causes a change in the structure 

 ind oecology of the plant. Chlorophyll having become useless is sup- 

 oressed or transformed into other brown, yellow, or brick-red pigments 

 apparently allied to chlorophyll, and these give to saprophytes a vivid 



