18 



THE AM Ell H AX X A TT' h'ALfsT 



[Vol. XLII 



perennial. Some are herbaceous, and some woody. Some 

 of them attack only the epitropic, and some only the apo- 

 tropic, portion of their host. Some are only partially 

 parasitic, obtaining only a part of their subsistence in 

 that manner, but a large number are completely parasitic, 

 and thus obtain their entire support from other plants. 

 The former obtain a part of their subsistence from the 

 soil as normal plants obtain all of theirs. They also de- 

 velop leaves and produce chlorophyl, but the complete 

 parasites, with exceptions to be mentioned, develop no 

 functional leaves and produce no chlorophyl, for com- 

 pletely parasitic plants do not need to produce it. New 

 organic substance, elaborated as already has been men- 

 tioned, is of course necessary to the existence of the 

 normal plants which produce it. It is no less necessary 

 to the existence of the parasites, but they, not being able, 

 or not predisposed, to produce it for themselves, obtain it 

 by robbery from other plants. All of them are so de- 

 praved that they acquire special hereditary habits of 

 rapine, modify their structure, and even develop special 

 organs with which to accomplish their thefts. The defi- 

 ciencies and modifications of structure are correlated with 

 the respective kinds of parasitism, and they are invariable 



structureless, not being differentiated into cotyledons, 

 radicle and plumule. Indeed, some of the most vigorous 

 of the parasites originate from embryos that apparently 

 represent only a moiety of the normal phenogamic embryo. 



The leaves of normal phenogams are properly regarded 

 as the chief organs concerned in the production of chloro- 

 phyl, but if my assumption is correct that the agency of a 

 structural root is a precedent necessity in normal cases 

 of such production, the functional leaflessness of a para- 

 sitic phenogam is a direct consequence of its rootlessness. 

 That is, because a rootless phenogam can produce no 

 sufficient quantity of chlorophyl, and because it procures 

 its new organic substance bv theft, it has no use for 

 leaves. Therefore, those leaves which it morphologically 

 inherits remain undeveloped or functionless. This is the 



