MYCOLOGICAL BULLETIN 



No. 30 



JV. A. KcUcrman. Ph. D., Ohio State University 



Columbus, Ohio, March 15, I'JOo 



Parasitic Fungi. — It is easier to tell the difference between sapro- 

 phytic and parasitic fungi than it is to draw the line of demarkation in all 

 cases. Some fungi are purely parasitic and others are just as distinctly 

 saprophytic. That is, «ome species (parasites) take their food directly and 

 exclusively from living plants and animals: the saprophytes, on the other 

 hand, live on decaying organic matter. It is now known that some sapro- 

 phytic forms may for a time at least adjust themselves to a parasitic mode 

 of life — or as a botanist would say, they are faciiltatizc-parasites. Again, 

 some parasites are able to live for a time on dead organic matter — they are 

 therefore facnltativc-sapropliytcs. Some species of a given genus may be 

 parasitic, and others — though of the same genus — may be classed with the 

 saprophytes ; but such cases are not numerous. The common Mushrooms and 

 Toadstools — for the illucidation of which this Bulletin has its reason d'etre 

 — are usually very conspicuous, exhibit manifold forms, and varied color- 

 ings. Ihe parasitic species on the contrary, are mostly inconspicuous, 

 indeed microscopic, and known chiefly by their devastations. Innumerable 

 discolored areas on leaves, conspicuous spots because the tissue is dead 

 and bleached or may be peculiarly colored, may indicate the presence of a 

 parasitic fungu- — yet to detect the latter a hand lens may be necessary, 

 and only with the aid of a compound microscope can the form and struc- 

 ture of the fungus l)e determined 



Tig. 05. I'n yi.-i.acii'-o-r.\ MF.x-I•c.^'-^•.^. .\ p.irasitic funsiis on Adolpliia sent from 

 Ml xico. 'Ilie st< m ( l"is>. 1 ) is attacktti by tlu' fi'.njius and forms blackened areas. 

 I'isi're 'i show.> a ntction ibrougli tlie iiart of the stem wliich is affected and the stio'-iiui 

 (as tlie black solid part of the fungus is callid) is seen to be occupied by cavities in 

 which as'ci and ascospi res are fornnd: the latter are illustrated in Figures 3 and 4. 

 I'igi'.re 5 s-hows some f^f the /'(i-((j/'/i'-v-.<r.> which are mi.xtd with the as'ci. This, a new 

 siiecies when collected last summtr, was sent by I'roftssor .\. h. Ilerrera, of ^^exico 

 City, Me.<ico. 



University Bulletin, Scries 9. No. 8. Entered as Second Qass Hatter, Post-office at Columbus. Ohio 



