THE miKXOUAMOrS PARASITES 



By DR. CHARLES. A. WHITE 



The object of this essay is to describe in a popular 

 manner the chief characteristics of the known kinds or 

 groups of phenogamous parasites, to show their relation 

 to one another and to normal phenogams, and to discuss 

 their structure and habits with reference to the probable 

 manner of their origination. In order to make a popular 

 statement of the characteristics of each group of these 

 abnormal plants and to discuss them clearly it is first 

 necessary to summarize briefly the elemental structure 

 and physiological characteristics of the normal pheno- 

 gams. I have chosen to do this in verbal terms a part 

 of which are somewhat unusual, but which are believed to 

 be specially appropriate to discussions of this kind. 



The elemental parts of a normal phenogamous plant, 

 are root, stem and leaves, the beginning of the differentia- 

 tion of which structures is distinguishable even in the 

 embryo; and to these are added, at the maturity of the 

 plant, flowers and fruit. Every normal phenogam also 

 consists of two incremental parts, an up-growing and a 

 down-growing part, respectively, the latter entering the 

 soil to form the roots. The normal phenogamous plant 

 performs all its physiological functions within, and for, 

 itself and lives independently of all other plants except 

 in the matter of competition with them for the benefits 

 of soil, moisture and sunlight, but the parasites escape 

 the performance of those functions so far as nutrition is 

 concerned. The normal plants derive the materials for 

 their subsistence and growth from inorganic sources and 

 elaborate them within their own tissues for their own use, 

 producing thereby their new organic substance, but the 

 parasites rob other plants of that substance in its elab- 



