24 THE LARCH CANKER 
In addition to this experimental work Hartig added to 
Willkomm’s description of the mycclium in the bark, 
phloem, and wood of the larch. In the wood it was dis- 
tinguishable in the medullary rays, the resin ducts, and 
tracheides. In the sieve tubes he noticcd that the hyphac 
bore short extensions, with or without a few branches. 
He added little to our knowledge of macroscopic features 
of the disease, with the exception of some observations on 
the resin flow from the surface of the bark, but he provided 
some interesting measurements of the growth of canker in 
the longitudinal direction of the stem. They were taken 
from three isolated cankers from different altitudes, and 
though they were insufficient for a just comparison of the 
rates of growth at these levels, they nevertheless give some 
indication of the growth of a canker gencrally. The cankers 
were measured at— 
1. Steinach (Tyrol), 1,300 m. (4,300 ft.) above sca-level. 
2. Grafrath (near Munich), 700 m. (2,300 ft.) above sea- 
level. 
3. Brunswick Forest Garden, 170 in. (550 ft.) above sea- 
level. 
The results were as follows : 
After Sleinach. Grafrath. Brunswick. 
years cm. cm. cm. 
1 1-0 1-2 1-0 
2 2-2 3-9 3-3 
3 7-0 6-5 $1 
4 9-4 9-2 10-5 
5 11-6 13-1 13-0 
6 16-8 17-7 14-7 
7 20-2 20-6 16-0 
8 21-8 24:8 16-9 
9 24:6 30-5 19-3 
10 27:0 —_ 23-0 
The importance of Hartig’s work on tree pathology will 
be best appreciated when it is observed that reference has 
been made to contributions by this author under the head 
of nearly every disease mentioned in this book. The vast 
field of research covered by Hartig appears still more 
remarkable if we remember that when he started on his 
work the subject was in an entirely chaotic state, and it is 
