554 THE POPULAR SCIENCE MONTHLY 



and impressions of one and perhaps two -pedes found in the miocene 

 rocks of Oregon, and in those of the upper miocene of the Colorado park-, 

 show that Castanea, which already existed in Europe in the cretaceous 

 period, once inhabited western North America, whence it has now dis- 

 appeared. '" 



Coming now to the condition of the chestnut tree to-day, let us first 

 figure up its liabilities, i. c, those diseases and injuries from which it is 

 prone to suffer, and then set down on the. other side of the balance sheel 

 its assets, i. c, those inherent qualities which accrue to its advantage 

 in the struggle for existent 



It is a significant fact that both the European and the American 

 chestnuts have been attacked in recent years by serious diseases which 

 have attracl it deal of attention here and abroad. In Europe the 



disease known as the Male dell' Incliiost.ro and various other troubles 

 have very seriously affected the European chestnut. 



In the United States, the well-known bark dist ase, discovered in 1904 

 near New York City, has already caused enormous damage to the chest- 

 ithern New England, New York, New Jersey, Pennsylvania, 

 Delaware and Maryland, and it also occurs in Virginia and West Vir- 

 ginia 8 (Fig. 1). It is unnecessary hi scribe this trouble in de- 

 tail, as excellent accounts of it have already been published and are i asily 

 available. 9 It is sufficient to state that it i- caused by a fungus which 

 grows in the living bark of the tree, gaining an entrance through wounds 

 or openings of any sort in the bark. As the fungus grows, it kills the 

 bark, and by gradually inert asing the radius of its operations, eventually 

 reaches around the trunk or branch which it entered, in this way 

 girdling it. 



"When this disease was first discovered, and its disastrous nature 

 realized, one of the first questions that are that of the source of the 



causal fungus. Where did this fungus come from ? "Was it a native 

 fungus, or was it brought into this country from abroad? Tt was easily 

 seen that the answer to this question was of fundamental importance, 

 for if the fungus was a native species, then its sudden attack was evi- 

 dently due to unusual environmental factors of some sort, and with the 

 recurrence of the normal conditions the virulence of the attack would 

 cease. On the other hand, if the fungus were an imported parasite, there 

 would be no telling where its depredations would end. 



Those who held to the first theory, i. e., that the fungus was a native 



s The disease has also been recently reported in a nursery in North Carolina. 

 See Metcalf, Haven, "The Chestnut Bark Disease," Jour, of Heredity, 5: 8-18, 

 1914. 



9 Metcalf, Haven and Collins, J. Franklin, ' ' The Control of the Chestnut 

 Bark Disease," U. S. Dept, of Agr., Farmer's Bull., 467: 1-24, 1911. 



Clinton, G. P., "Chestnut Bark Disease," Rept. of Conn. Agr. Expt. Sta., 

 1912, 359-453; pis. 21-28, 1913. 



