71 



theory that tliey have been introduced wlieii ihey produce sudden 

 and virulent epidemics, as in the case of the potato rot. The 

 presumption, I say, is in favor of this theory, l)ut a presumption 

 it should be borne in mind is not a certainty. If Diaporthe para- 

 sitica is not a species new to science, what is it, and where did 

 it come from? The microscopic structure of the chestnut tree 

 fungus as we now know it, is well known, and its habit and its 

 reproductive organs have been described and figured in many 

 l)ul)lications accessible to everyone, ^^'hat, however, is not so 

 generally known is what has been written in times i)ast on fungi 

 f(»nn<l on chestnut trees in dillerent countries, and a review of 

 what is kn<»wn to mycologists in this conn(?ction may be instruc- 

 tive although, it must be a(liniti(Ml. the subject is not very easy 

 to follow. On account of dried specimens in the older herbaria 

 and a summary of the often obscure and conflcting descriptions 

 to be found in old treatises, even if desperately dull, will enable 

 us to form certain practical conclusions. 



When I first received fresh specimens of the fruiting fungus 

 of the chestnut tree I was struck by their great resemblance to 

 what is generally known in American herbaria as EtuJoih'ui 

 (jyrosa. Unfortunately most of the specimens of that species in 

 lierbaria are sterile and from the habit alone one cannot be sure 

 of the species of a fungus of this group. The fresh fungus also 

 recalled a specimen I had seen in an Italian collection, and (ui 

 looking it up and comparing it miscroscopically with the fresh 

 material, I found the two to be identical. The gross structure 

 and the characters of the spores and a.sci were the same in both. 

 The Italian specimen to which I refer is Xo. OSfi, First Series of 

 the Erhario Crittogamico Italiana, issued in 18G3. The label 

 states that the fungus grew on chestnut trunks at Locarno on 

 Lake Maggiore, where it was collected 1»y Daldini in \SiVl. The 

 name there given is Endoihia radicaJis, but the question of the 

 name need not be considered at present. As other l>otanists 

 have examined the specimen just mentioned and agree as to 

 the identity of the En doth ia radicaUs and the Diaporthe parasi- 

 tica, some having already expressed their opinion in print, we 

 may state definitely that our American chestnut tree fungus does 

 not appear to be new but to have been known on chestnuts in 

 Italv fiftv vears ago. 



