ALBUGO PORTULAC& OR A. CANDIDA. 67 



interesting feature of the plant is its habit of life and 

 the adaptations which have been induced thereby. It 

 is throughout its existence a complete parasite, growing 

 and feeding upon plants of very high organization. Being 

 no longer required to elaborate food for itself, finding it 

 always at hand and of superior quality, it possesses no 

 chlorophyll bodies by which it might construct its own 

 food, and is therefore quite colorless. As it grows it sends 

 its branches throughout all the softer tissues of the host. 

 They do not penetrate the cells directly, however, but 

 push about between them, and in order to extract the 

 food readily, especially in the newest portions where rapid 

 growth is taking place and food is therefore abundant, 

 send out slender haustoria which penetrate the adjacent 

 cells and expand into minute absorbing bulbs. 



The means of distribution which the plant possesses 

 in its oospores is rather limited, being inferior to that 

 of Spirogyra and Vaucheria; and when once established 

 in a host it is debarred from all further locomotion, such 

 as the moving water imparts to the spores of some other 

 plants. In order to secure certain and extensive distri- 

 bution, therefore, and to provide for a succession of 

 crops through the growing season, it produces conidio- 

 spores or summer spores in the greatest profusion, which 

 being light and dry are easily blown about by the wind, 

 and are ready to germinate at once. The thin wall and 

 active protoplasm of the conidia, from which they derive 

 this advantage, render them at the same time short-lived, 

 so that if a conidiospore does not find favorable con- 

 ditions for growth within a few hours after reaching 

 maturity it perishes. The conidia germinate in water, 



