144 COMPENDIUM OF GENERAL BOTANY. 



to both saprophytes and parasites. If the food-supplying organism 

 is alive and injuriously affected by such a relation, it is recognized 

 as parasitism. Vegetable parasites are either endophytic or epi- 

 phytic, that is, either growing within the plant or attached to the 

 outer surface. If the organic substances belong to dead organisms, 

 the organisms living upon them and taking nourishment from 

 them are known as saprophytes. Theoretically these groups may 

 be clearly separated, but actual observation teaches that the two 

 modes of life-activity may become interchanged or may occur side 

 by side. 



Fungi are entirely dependent upon organic food, since they con- 

 tain no chlorophyll. In the numerous fungi which infect living 

 plants, but which can only reach their maximum development on 

 dead plants, parasitism and saprophytism seem to alternate. 



The few phanerogams devoid of chlorophyll are also dependent 

 upon assimilated or organic food ; for example, the orchid Epipo- 

 gon Gmelini is a saprophyte, Cuscuta is a parasite ; Monotropa is 

 said to be both parasitic and saprophytic. Viscum album, the 

 well-known mistletoe, is evidently parasitic, although its green 

 leaves have the power of assimilation ; Neottia nidus avis is a sap- 

 rophyte and has some power of assimilation owing to the chloro- 

 phyll in the reduced scaly leaves. 



Parasitic phanerogams present remarkable anatomical arrange- 

 ments, which enable them to take up assimilated food- substances. 

 The details of this adaptive arrangement were studied by SOLMS- 

 LAUBACH, and L. KOCH. There are three characteristic parts to 

 the organ which serves to absorb the food-substances; namely, 

 the haustorium, the sucker, and the absorbing -cells. These are 

 shown in figure 85, A and B. B represents the absorbing 

 cells, s the sucker somewhat magnified ; w is the root of the host- 

 plant. 



In regard to the parasitic fungi which have the power of pene- 

 trating cell-walls, it is to be noted that this phenomenon is associated 

 with the excretion of ferments having the property of dissolving 

 suberized as w^ell as unsuberized cell- walls. To the Schizomycetes 

 (bacteria) especially, various fermentative activities are ascribed, not 

 only for the purpose of dissolving cell-membranes but also for dis- 

 solving albuminous substances. The fact that chlorophyll-bearing 

 plants occur parasitically on rhizomes and roots of other plants 



