ENDOTHIA PARASITICA AND RELATED SPECIES. 71 



become acid from underground drainage. Chestnut trees on soils derived 

 from other alkaline rocks show less blight than is found in the trees on shale 

 soils with limestone underneath. 



On the other hand, Detwiler (24, p. 67) reports observations in 

 the Lizard Creek valley which seem to show that these relations do 

 not always occur. He says — 



A belt of limestone borders Lizard Creek valley on the south, and the per 

 cent of infection is as high in that region as elsewhere. Infection centers 

 have been found near limestone quarries, where the roots of the chestnut pene- 

 trated to bedrock. 



Actual proof or disproof of the truth of this idea was peculiarly 

 difficult, since chestnut is but rarely found growing naturally on 

 calcareous soils. During the summer of 1914, however, a careful 

 study of the chestnut on certain portions of limestone areas in west- 

 ern Maryland and western Connecticut was made. These localities 

 were chosen because they were convenient in connection with other 

 work, the blight had been present for several years in both States, 

 and thorough State geological surveys made the location of the lime- 

 stone areas very eas}^. The two States also are sufficiently far apart 

 to eliminate sources of error that might arise from local weather 

 conditions. 



In western Connecticut chestnut was abundant on glacial till over 

 the Stockbridge limestone of this region. Chestnut was also grow- 

 ing directly over limestone at various points near Danbury, Twin 

 Lakes, Chapinville, and Lakeville. Several localities near the latter 

 place were kindly pointed out by Dr. George E. Mchols. Near Dan- 

 bury every tree examined showed the blight in a more or less ad- 

 vanced stage, while near the other towns, all in the northwest corner 

 of the State, nearly 50 per cent of the trees were blighted. About 

 30 inoculations were made on sprouts in this region, and all 

 except two developed cankers quite as rapidly as did check inocula- 

 tions made on the trap ridge west of Hartford. 



Chestnut is very rare on the Shenandoah limestone in the Hagers- 

 town and Frederick valleys of western Maryland. A number of 

 chestnut trees were, however, located growing on limestone soil near 

 Frederick Junction and Adamstown in the Frederick valley. The 

 disease was already established west of Adamstown, where 20 per 

 cent of the chestnuts were either diseased or dead. Twenty-two in- 

 oculations were made on nine chestnut sprouts in these two regions, 

 and all developed typical cankers quite as rapidly as the checks made 

 in similar sprouts growing over Baltimore gneiss 50 miles east. 



RECESSION OF THE CHESTNUT IN THE SOUTHERN STATES. 



While it has been definitely proved that Endothia parasitica is 

 pathogenic on healthy chestnut trees, one of the points brought for- 



