266 Groom.—Remarks on the Oecology of Coniferae. 
3. Those that are less severe, and may be merely leaf-diseases from 
which the tree usually or always recovers. 
4. Others, concerning whose precise significance we are not fully 
informed, but which are probably largely not of first-class importance. 
In the table below, the first two classes are grouped together as severe 
and the last two as slight; the estimates of the severity or lenience of the 
diseases are my own. 
The dicotylous trees are infected by 15 severe fungal diseases, of which 
11 are limited to them, while the Coniferae are attacked by 25 severe 
fungal diseases, of which 21 are restricted to them: the remaining 4 
affect dicotyledons and Conifers. Of the 15 attacking dicotyledons, 8 are 
wood-destroying Fungi that do not infect coniferous wood; while of 
the 25 serious fungal foes of Coniferae only 6 are limited to wood (there 
are others attacking both wood and cortex). As the Fungi attacking heart- 
wood can hardly be regarded as of first-class severity, if they were excluded 
from the lists the disparity between dicotyledons and Conifers would be 
further increased. 
Species. 
Number of parasitic fungal diseases. 
Enumerated by Hartig. 
Enumerated by Von Tubeuf. 
Severe. 
Slight. 
Total. 
Severe. 
Slight. 
Total. 
Abies pectinata 
12 
2 
14 
14-15 
3-2 
17 
Picea excelsa 
17-18 
4-3 
21 
T 9 
O 
O 
22 
Pinus sylvestris . 
10-11 
4-3 
14 
18-20 
6-4 
24 
Larix decidua . . 
8-9 
2-1 
10 
9-10 
2-1 
11 
Quercus Robur 
IO-I 1 
3-2 
13 
10 
T 4 
24 
Fagus sylvatica . 
4-5 
3-2 
7 
6 
9 
15 
Betula alba. 
2 
4 
6 
3 
14 
17 
Carpinus Betulus 
j 
2 
3 
2-3 
7-6 
9 
A Inns glu tin os a . 
2-3 
4-3 
6 
i -3 
12-10 
T 3 
Fraxinus excelsior 
I 
0 
1 
i -3 
6-4 
7 
Similarly, in regard to insect foes, I have drawn up lists of the various 
insects attacking forest trees in Europe, using as the source of information 
* Lehrbuch der Forstinsektenkunde ’, by Judeich and Nitsche: the results 
are given in the columns 2-7 of the succeeding table. These diseases 
I have ranged into several classes: (a) severe, and attacking young plants 
(seed-beds and nurseries, &c.) ; ( b) slight, and attacking young plants ; 
(c) severe, and attacking older trees; ( d ) slight, and attacking older trees. 
There is a certain vagueness in the classification because I have had to use my 
judgement, first, as to whether the disease is severe when it does attack the 
tree, and secondly, as to whether it is sufficiently common on the tree to be 
reckoned as a menace ; but diseases caused by insects that rarely attack the 
species I have reckoned as ‘ slight \ In order to check my estimate I have 
drawn up the list of insect foes that attack the same species of forest trees 
