1890.] PUBLIC DOCUMENT — No. 33. 201 



We may pass now to a more particular account of the 

 o:roups of chlorophyll-less plants already mentioned. 



The Slime ^Moulds comprise a comparatively small num- 

 l)er of plants, most of which are strictly saprophytic in their 

 mode of life. A few of the simpler ones, however, are 

 parasites, and their life history may be briefly sketched. 

 They pass the winter or other unfavorable period in a so- 

 called resting state, in which condition they appear as tiny 

 globular bodies, each consisting of a mass of living matter, 

 surrounded by a tough, firm coat. When warmth and moist- 

 ure return, these outer coats crack open, and the living 

 masses escape and begin to actively creep about, seeking for 

 the plants on which they are able to live. Failing in this 

 search, one of these tiny creeping masses soon dies ; but, 

 if successful, it penetrates the cells of the host plant, and 

 proceeds to grow and mature at its expense. Toward the 

 end of the growing season, the masses of living substance, 

 which have greatly increased in size and now occupy the 

 interiors of cells of the host whose contents they have 

 absorbed, break up into many very small portions, each of 

 which enters the resting state by becoming surrounded with 

 a tough coat, and so awaits the next season. These organ- 

 isms are clearly of the simplest nature, and it would perhaps 

 be better to call them simply oir/anismft, than to try to 

 assign them a place on either side of the shadowy and 

 indefinite line which separates the lowest plants and ani- 

 mals. By nearly universal consent, however, their study 

 is assigned to the botanists. The most important member 

 of this group, economically, is perhaps the parasite which 

 causes the "club-foot" of cabbages and turnips, incidentally 

 described in the article on " Potato Scab," in the report of 

 this station for 1888. 



The Bacteria, or "germs," include the smallest known 

 organisms, with both saprophytic and parasitic forms, and 

 perhaps many which can live in either way. They consist 

 of minute spheres, rods and threads, whose vital activity is 

 the cause of many most remarkable phenomena. Among 

 those which live saprophytically, one form produces the 

 putrefaction of dead organic matter ; another causes the 

 souring of milk ; another, the change of alcohol into acetic 



