EFFECT OF I'AKASlTir 1-TNUl .N THEIR HOST. lM 



by pustules of Vrocysti* violae, the mycelium of which had 

 perennated in the stem. Kerner in his ' Pflanzen-leben J 

 mentions a similar case where flowers of /'//' //<>//</ chisiana and 

 /'. minima attacked by Ur<> //'//<< x primulae integrifoliae unfolded 

 prematurely in autumn. 



E. PRESERVATION UK THK H"-I-|'I.AXT AMI UK Husx-Tissi K-. 



(( ''NSKKVATIoN.) 



Iii contrast to those parasites which attack a plant, or parts of 

 it, and immediately kill it or otherwise exert a direct destructive 

 influence, we have these which live for a longer or shorter period 

 with their host without producing such an effect. Cohabitation 

 <>t' this kind may last only for a short time and terminate with 

 the first reproductive period of the fungus, or it may last for 

 years as a perennating symbiosis, or as a perpetual one like that 

 of lichens. 



This phenomenon is particularly conspicuous amongst the 

 I'redineae. These throughout their whole development adapt 

 themselves to an existence with living host-cells, so that the 

 latter die only after the reproduction of the fungus. Frequently 

 the mycelium lives in perennial organs for a length of time, 

 veil for many years. The attacked parts are of course injured 

 to a certain extent, and hypertrophy of the most varied kind, 

 accompanied by characteristic phenomena, may lake place, yet 

 this only towards the termination of the period ot development. 



The Ustilagineae are in a similar manner adapted to an exis- 

 tence in living organs, and there produce their spores. At the 

 time of spore-formation and liberation they are deadly eiiemie- ,f 

 their host-tissues, yet previous to this they \e-etate in Un- 

 living tissues with little or im apparent injurious clleet. Sume 

 like C.-tfiln,/,, i>< r> ini'Kix, even pass the winter in the living host- 

 tissue without killing it. 



The individual species of the llysteriaceae, Discomycetes, 

 J'vicimmycetes, Ilymenomyectes, and lower fungi differ \vr\ 

 much in their act inn: many of them inhabit living tissues fur a 

 length of time without injurious effect, while not a few, like the 

 1-Aoasceae, even j.erennate from year to year. The Lialls pro- 

 duced as a re-ult of /J,;,/ l ,i'i/ii/ni dn imt die till the fungus has 



it-elf. It is unnecessary at this place to give details 



Kiliti.ni, natural Hittory of Plant* (Oliver), n., p. "'-">. 



