DAMPING-OFF IK" FOREST NURSERIES. 7 
tirely on mechanical puncturing for its progress from cell to cell. 
Hartig (61, p. 147-150) shows a fungus which he does not name, but 
which is evidently a species of Fusarium, dissolving the young un- 
cuticularized epidermis of pine seedlings; but he states that it can 
not so dissolve older epidermis. The increased protective value of 
the epidermis of older plants can only in part explain the immunity 
most of them develop against serious attack by damping-off organ- 
isms, as lesions already started or which may later develop from the 
infection of young roots are unable to extend into the older parts 
of the plants. 
It may be mentioned here that the writer in a very preliminary 
test found strains of Corticium vagum and Fusarium monili forme 
Sheldon which had been proved able to cause damping-off of pines 
also apparently able to destroy filter paper in inorganic salt solu- 
tion, while Pythium debaryanum seemed not so able. Ruhland 
(116), on the other hand, found the strain of the " vermehrungspilz " 
(Corticium vagum) which he tested to be very weak in cellulose- 
destroying ability as compared with Botrytis cinerea. 
DAMPING-OFF OF CONIFERS. 
HISTORICAL. 
While the losses from damping-off in seed beds of dicotyledonous 
tree species are occasionally serious and in the case of beech in 
Europe have required considerable study, they have been so far 
overshadowed in this country by the losses in coniferous seed beds 
that practically all the attention thus far, both as to etiology and 
measures of prevention, has been devoted to the disease in conifers. 
The literature on the damping-off of conifers is considerable. 
A large part of it, because of the extensive early development of 
plant pathology and forest planting in Germany, has been writ- 
ten by Germans. A large portion of the German articles on it 
was either by foresters or by botanists in the day when most patho- 
logical work was of the reconnaissance type. Therefore, while the 
work of one of the best known of the parasites on coniferous seed- 
lings was noticed in Europe as early as the eighteenth century (21, 
p. 252-253) most of the European data available are observational. 
The only fungi which were at all definitely connected with the dis- 
ease on conifers seem to have been Fusarium (Fusoma spp.) and 
Phytophthora fagi (P. omnivora De Bary in part). The damping- 
off Rhizoctonia was described in Germany in 1858 and Pythium de- 
nary anum in 1874 ; the fact that neither of these, important in conif- 
erous seed beds in both the eastern and western United States, has 
ever been reported from conifers in Europe is perhaps the best evi- 
