Graves: Parasitism in Hymenochaete Agglutinans 281 
On the other hand, a branch originating just below the earlier 
parts of the infection (Plate 145, fig. 4) showed corresponding 
increases in the growth in length of its main shoots, as may be 
seen from table II. 
TABLE II 
Comparative Length of Annual Growths of Branch Below Girdled 
Portion^- 
1912 
1913 
1914 
2'4 inches 
2j4 inches 
9 inches 
J4 inch 
“ 
14 " 
if 4 “ 
1 H 
1 inches 
3^4 “ 
Again, examination of the fungus at the point of contact of the 
two plants showed periods of growth which could be correlated 
pretty well with the facts just mentioned. Apparently three years 
of growth were present, each one marked by a different color in 
the fungus. The growth of the first year, i. e., 1912, was black, 
that of 1913 a grayish hue, while the recent growth of 1914 was 
colored a creamy-yellow in the outer portions, shading into a deep 
rich-brown toward the inner parts. (Plate 145, figures 2 and 5.) 
On the evidence presented by these observations, therefore, the 
girdling from the fungus first commenced in 1912. In the fol- 
lowing year the effect of this girdling began to show itself in a 
marked decrease in the vigor of the year’s shoots, a result which 
was enhanced by the continued development of the fungus. In 
1914 the action of the fungus had progressed so far that the plant 
could make only a feeble growth, which soon died when all com- 
munication with the lower parts of the stem was shut off. 
Microscopic examination showed clearly the presence of num- 
erous hyphae among the living cells of the stem. For this study, 
sections were cut through the lower part of the region attacked, 
where it was partially overgrown with the fungus. (Plate 145, 
figures 2 and 5.) At this point, as would be expected, much of 
the stem was still alive. Yet the cambial region in many places 
had taken on a brownish color, and here, as well as in the living 
medullary ray cells of the wood, the presence of mycelium could 
be clearly demonstrated. A common mode of entrance of the 
1 As shown in Plate 145, Fig. 2, this branch had already, in 1914, become 
invested with the fungus and probably would have succumbed in its turn. 
