LYSICHITON CAMTSCHATCENSE (l.) SCHOTT 207 
case in point. Haglund (13) has in a most interesting and convincing 
way demonstrated that the stools of the forest beds in most of the 
Swedish peat bogs have been on fire. By burning, the peat became 
unsuitable for the growth of forest vegetation, while on the other hand 
Sphagnum found a very favorable habitat and replaced the forest. 
Furthermore, w^ith the disappearance of the forests an elevation of 
the level of the ground water takes place and hydrophytic conditions 
increase, resulting in a corresponding change in vegetation. Burns 
(3) gives an interesting account of the effect of alternating dry and 
wet periods of short duration on bog vegetation in the Huron River 
Valley. His description of the alternating layers of Sphagnum and 
Polytrichum peat corresponding to the wet and dry periods of previous 
years is particularly illustrative. 
Examples of the destruction of forests under the influence of 
increased humidity due to local conditions can also be cited from 
this region. Lake Kapowsin, near Tacoma, originated by the damm- 
ing up of a river probably by beaver dams and by subsequent swamp 
vegetation. The surrounding forest was flooded, and the trunks 
sticking up out of the water bear witness of the flood. Today floating 
bog vegetation occupies part of the lake's surface. Examples of a 
somewhat similar nature have been described repeatedly (for instance 
by Nilsson, 17). The above-mentioned sedge bog meadow on Mount 
Constitution may also be taken as an example. It occupies a deep 
pocket in the mountain. In the transition zone between the bog and 
the adjoining forest almost every tree is killed. The fringe of dead 
trees is as marked as if cut out with a knife. As the swamp vege- 
tation increased and filled up the concavity it reached the forest which 
had established itself on the slopes with the result that this was killed 
either by the water itself or by toxic substances in the stagnant water. 
In conclusion I want to call attention to the different ways in 
which plants enter and have entered the Green Lake bog. In ad- 
dition to Lysichiton there occurs in the bog an undetermined Carex 
species which probably also is a relict from the swamp stage. It is 
usually sterile and illustrates the tendency of plants to become sterile 
or xerophytic in structure when growing under bog conditions as 
shown by Lindman (15) and Nilsson (18) for a number of plants and 
confirmed by the cultural experiments of Transeau (26) and Dach- 
nowski (9). 
A point fully as interesting as the relicts in the bog is furnished 
