ENDOTHIA PARASITIC A AND RELATED SPECIES. 59 



PRESENT DISTRIBUTION OF ENDOTHIA PARASITICA IN AMERICA. 



The present range of Endothia parasitica in America, as shown by 

 the map (fig. 4), is probably merely the extent to which it has been 

 able to spread in the time since it was first introduced. 



Whether Endothia parasitica was introduced into one locality or 

 several is uncertain, but the studies of Heald (40, 41) and others have 

 shown clearly that the spores of E. parasitica are carried by the wind, 

 by insects and birds, and on nursery stock, which would account 

 for its wide distribution and for its occurrence in isolated localities, 

 long distances away from the main body of the disease. It also makes 

 it seem probable that the fungus w r ill continue to spread with some 

 rapidity. 



Certainly, there is no evidence that any factor, climatic or other- 

 wise, is likely to prevent the spread of this fungus into the large area 

 of chestnut south of its present range. On the contrary, the duplicate 

 inoculations made by the writers show clearly that the fungus grows 

 more rapidly at the southern limit of its present range than farther 

 north, where it is much more common. The longer growing season 

 in the South is also no doubt an important factor. 



In this connection, it may be noted that Koppen (46), in his map 

 of the vegetation regions of the earth, places the portion of China 

 where EndotMa parasitica has been found indigenous in the same 

 climatic region as that portion of the United States where it is now 

 doing such destructive work. He designates this region as the 

 " Hickory " division of the mesotherms. 



HOST RELATIONS OF THE SPECIES OF ENDOTHIA. 



ENDOTHIA GYROSA. 



Endothia gyrosa occurs commonly on Liquidambar, Fagus, and 

 Quercus, occasionally on Castanea, and has been found on Vitis in 

 Alabama, but the writers were unable to obtain fresh material from 

 this host. 



While Fagus and Quercus are, of course, closely related, it seems 

 remarkable that a fungus should be abundant on hosts so different 

 as Liquidambar and Quercus, yet so rare on any other host as to be 

 only once reported. It seemed possible, indeed, that the fungus on 

 Liquidambar, while morphologically and culturally identical with 

 that on the various other hosts, might prove to be physiologically dif- 

 ferent. In order to obtain more definite information on this point, 

 several series of cross inoculations were made. 



It had been observed that Endothia gyrosa was found most fre- 

 quently on the cut or broken ends of branches or on exposed, bruised, 

 or broken roots. In making inoculations, therefore, a small branch, 



