No. 493] THE PHENOGAMOUS PARASITES 



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the green vegetation of the earth. Abnormal phenogams 

 constitute only a very small proportion of the great mass 

 of vegetation, and yet the aggregate number and variety 

 of their forms is really very great. Three general kinds 

 of abnormal phenogams are recognized, namely, para- 

 sites, saprophytes and symbionts. They have certain 

 characteristics in common and often are visually similar, 

 but they differ materially from one another in the manner 

 of procuring their subsistence, and the habit of each of 

 them in that respect may be either partial or complete. 

 That is, a phenogam may be partially parasitic, sapro- 

 phytic, or symbiotic, and partially normal; or parasitism 

 may be associated in one and the same plant with sapro- 

 phytism. While my chief object is to discuss the para- 

 sites, it will aid in defining their characteristics to pre- 

 sent a brief statement of those of the two other kinds of 

 abnormal phenogams. 



Saprophytes derive their subsistence from dead organic 

 matter in the soil which has not reached the stage of full 

 decomposition. That matter yields a soluble portion to 

 the food-sap which the plant obtains by its roots in the 

 usual manner and, after some reelaboration, that portion 

 is applied by the plant as new organic substance in the 

 building of its tissues. Saprophytes, like vultures, hyenas 

 and epicures, take their food in a partially decomposed 

 condition and thrive upon it. Doubtless many plants that 

 are properly regarded as normal arc really in part sapro- 

 phytic when their roots have access to organic manures, 

 but only completely saprophvtic phenogams are here re- 

 ferred to. It is claimed by some investigators that com- 

 pletely saprophytic phenogams sometimes produce chloro- 

 phyl and develop green leaves, but those here discussed 

 produce no chlorophyl, develop no functional leaves, and 

 are therefore not green in color. Their reproduction, both 

 parturital and blastemal, is normal and they grow from 

 their roots in the soil like normal plants, with none of 

 which are their vital relations antagonistic. Completely 

 saprophytic phenogams, which only are now particularly 

 referred to, are comparatively rare, especially in ordi- 



