224 BROWN. 
the base of the shoot is embedded, and in the early stages a dome- 
shaped projection of the bark which surrounds the apex of the 
developing shoot. 
The differentiation of the growing point takes place long 
before the shoot breaks through the bark of the host and is 
preceded by the formation of a cap of tissues which becomes 
separated from the apex. 
The vascular bundles are concentric and end in the general 
region of the cambium of the root. Some of the xylem and sieve 
tubes are connected directly with the corresponding elements of 
the host. 
The enlargement of the parasite finally produces cracks in the 
bark of the host through which the parasite grows. The bark 
around the flower gradually disappears but the base of the 
shoot remains embedded in a mass of xylem and bark formed 
by the root of the host. 
The excessive production of xylem and bark by the root gives 
the parasite a firm anchorage and abundant food supply while 
the parasite does not destroy the xylem of the host to any con- 
siderable extent. The taking of food from the cells of the root 
would appear to be the chief damage which the parasite does to 
the host. 
