CYSTOPUS CANDID US. 51 



is to be sought in the nature of the parasitism exhibited 

 by Cystopus. Whatever may be the full significance 

 of sexuality, many facts point to the belief that it is 

 an expedient for the reinvigoration of the exhausted 

 energies of the plant. 9 Cystopus is intimately asso- 

 ciated with a plant immensely above it in the scale of 

 development and of a correspondingly higher poten- 

 tiality. Its vigor is in direct ratio to that of its host, 

 which latter far exceeds the requirements of the simple 

 parasite. The energy which the parasite receives 

 from its host may take the place to some extent of that 

 usually obtained through the sexual process. It there- 

 fore seems justifiable to believe that while the anther- 

 idia are in most cases formed, the fertilizing tube is 

 often either not present or functionless, i. e. that we 

 have the production of oospores without the aid of the 

 male element, a method known as parthenogenesis, 10 a 

 difficult matter to establish by observation. This view 

 is rendered more probable by the fact that it is the 

 customary mode of reproduction in some of the closely 

 allied Saprolegniae " which are mostly parasitic for at 

 least a part of their life upon insects, a still more 

 highly organized food than that obtained by Cystopus 

 and its immediate allies. 



9 Ward, Quart. Jour. Micr. Sci. xxiv, (1884), p. 303; Bot. Gaz. ix, 

 p. 146. 



10 Sachs, Text-book of Botany, 2nd Eng. ed., p. 902 ; Ward, 1. c., p. 

 307. 



11 Pringsheim in Jahrb. f. Wiss. Bot., ix ; DeBary, Beitrage zur 

 Morph. u. Phys. der Pilze, 4te Reihe, p. 73 ; Sachs, 1. c., p. 275. 



