336 BOTANICAL GAZETTE [NOVEMBER 
branches, even in the two-year old branches, it is evident that 
the resin canals are soon cut off by the cork cambium, and on 
drying become functionless. As in the normal, the resin canals 
are filled up by the ingrowing epithelial or surrounding paren- 
chyma cells. This may occur in one part of the canal only, 
causing the formation of resin vesicles in the part where tylosis 
has not begun. The vesicles originate in the same way as 
in the normal, by the peripheral and tangential division of the 
parenchymatic lining of the resin canal. The resin vesicles 
begin to form even in the first and second year diseased shoots, 
increasing in size, so that in five-year old branches vesicles or 
blisters are found 3 to 8™™in diameter. In five-year old normal 
branches vesicles are seldom found more than 1™ in diameter. 
The increase in size and number, as well as the earlier formation 
of the resin vesicles of the affected branches, is due mainly to 
the earlier formation of cork layers and the greater resin secre- 
tion. On account of the increased growth of the bark of the 
tumor, the witch broom vesicles not only reach their largest size 
here, but they dry up and become functionless sooner than in 
any other of the diseased branches above the tumor. Since the 
primary cortex of the tumor is earlier affected, dries up, and is 
cut off by cork layers, the resin canal communication between 
the diseased branches above, and the normal branch below the 
tumor, is cut off or closed, even during the first or second year 
of the infection. 
Secondary cortex.—The secondary cortex contains fewer sieve 
tubes, which are also smaller, often only one-half as long and 
broad as the normal. The radial walls are provided with fewer 
sieve plates. The sieve plates vary in size, but are usually 
smaller and more irregularly distributed. Fewer branching, 
bast fiber-like, sclerenchyma cells are present than in the normal. 
The protein conducting cells of the medullary rays are absent 19 
the diseased bast of Adies balsamea. The bast parenchyma cells 
are larger and more numerous, and are usually filled with cal 
cium oxalate and tannin. 
Wood.—The growth of the wood in the diseased annual rings | 
