190 Melanose and Stem-E'nd Rot [888 
although organic deposits occur down to the frost line. 
These deposits are lamelliform, and each appears to be con- 
tinuous from its lowest point to the surface of the soil. 
Whether they originated from the decay of roots that had 
penetrated this layer while it contained more water than it 
does now, or whether they were formed by slow seepage 
from the surface, cannot be decided from the information at 
hand. The occurrence of small landslides in which dry soil 
was found above and below the layer in which the slipping 
occurred, indicates, however, that water may move in a thin 
sheet of soil and either form these deposits by carrying or- 
ganic matter from the surface, or, finding them ready formed, 
traverse them to the deeper portions. Since these layers are 
rich in organic matter it is probable that their constituents 
would cohere when frozen, which is not true of the dryer 
soil about them. This may perhaps account for the state- 
ments often made that in the winter or spring, frozen soil 
may be encountered at the surface and also below it, in 
sheets, at intervals. 
Whether due to this drying and being frozen in the dry 
condition, or to other more obscure causes, the soil of this 
dry layer is often flocculated to such a degree that it resem- 
bles a mass of small clay pellets. Even after wetting this 
flocculated soil retains its spherulate character. 
THE GEOGRAPHICAL DISTRIBUTION OF THE CITRUS 
DISEASES, MELANOSE AND STEM-END ROT 
By H. S. Faworrr 
A general survey of the citrus districts of the United 
States and Cuba has shown. that the distribution-areas of 
some of the important fungus diseases are not coextensive 
with the areas where the host is cultivated. This fact is 
strikingly brought out by an examination of the distribu- 
tion of some of the diseases that have been present in these 
regions for a long time. 
