No. 493] THE PHENOGAMOUS PARASITES 17 



this connection. One can hardly doubt that the complete 

 symbiotic condition of those plants has been imposed by 

 the aggressive increase of the fungus from its original 

 condition of partial symbiosis, but the phenogam so fully 

 acquiesces in it that the deficiencies of structure and func- 

 tion which its imposed condition entails have become har- 

 monious with that condition and hereditary. Even the 

 embryo, at least in the case of Monotropa, or Indian pipe, 

 and probably also in that of Sarcodes, or the snow plant 

 of California, has lost its differentiation into cotyledons 

 and plumule. This is a significant coincidence with a 

 similar condition which prevails in the embryo of many 

 parasites, as will be shown in following paragraphs. 



Examples of complete symbiosis are few among pheno- 

 gams, the most common case being that of Monotropa. 

 All the older botanists believed, and some of them so 

 stated in their text-books, that the species of that genus 

 are parasitic upon the roots of woody plants. Later 

 authors often have stated that Monotropa is saprophytic, 

 but still later investigators have demonstrated that the 

 plants of this genus are completely symbiotic. It will be 

 a disappointment to the older plant-lovers not to find their 

 familiar acquaintance, the Indian pipe, discussed among 

 the parasites on the following pages, but the facts which 

 have been stated require its omission there. 



Whatever view one may take concerning the two kinds 

 of abnormal phenogams that are briefly defined in the 

 preceding paragraphs, he instinctively regards the para- 

 sites as a criminal class in the great communitv of honest 

 plants. Their methods of parasitism are so varied, and 

 each method is prosecuted with such vigor and con- 

 stancy, that it is necessary to review them with reference 

 to those habits rather than to similarities and differ- 

 ences of systematic structure. They all are at least ac- 

 quisitive in their relations with other plants, and some of 

 them are vigorously aggressive and raptorial. They all 

 derive new organic' substance from other plants, always 

 from living ones, and apply it directly in the building of 

 their own tissues. Some of them are annual, and some 



