198 "BOTANICAL GAZETTE [MARCH 
L. (skull-cap), Lysimachia terrestris (L.) BSP (loosestrife), Cam- 
panula uliginosa Rydb. (bog bell-flower), Galium Claytoni Michx. 
(bedstraw), Lycopus uniflorus Michx. (bugle-weed), Sarracenia 
purpurea L. (pitcher-plant), Drosera rotundifolia L. (round-leaved 
sundew), Iris versicolor L., Arethusa bulbosa L., Spiranthes Roman- 
zofiana Cham. (lady’s tresses), Habenaria dilatata (Pursh) Gray 
(white bog orchis), H. psycodes (L.) Sw. (purple-fringed orchis). 
Sphagnum is rare. The shrub zone is better developed than at 
Sucker Lake and includes two subzones: the outer, in which 
Chamaedaphne calyculata (L.) Moench is dominant and accom- 
panied by Andromeda glaucophylla Link and Salix pedicellaris 
Pursh; the inner, of Alnus incana (L.) Moench. Advance islands 
of shrubs are scattered here and there over the sedge mat, the 
outermost being composed of Chamaedaphne, and the inner of a 
nucleus of Alnus incana surrounded by a circular zone of Chamae- 
daphne (fig. 35). Seedlings of tamarack are frequent in these 
colonies. The subzone of Alnus incana fringes the outer edge of 
the bog forest, which here as usual is a mere line along the sides, 
but broader at the ends. The bog tree is the tamarack. 
3. Open bog stage: Raspberry Island bog 
Raspberry Island is one of the row that bounds Rock Harbor 
on the southeast, and is next in line to Smithwick Island, studied 
in connection with the climax forest. Its upland forest cover was 
originally like that of Smithwick, but unfortunately this has been 
largely fire-swept, the bog area, however, having escaped unharmed. 
The island consists of two parallel ridges of the typical Isle Royale 
kind, bounding a narrow depression, closed at both ends by beach 
ridges, which contains the bog area. The outer ridge is the more 
massive of the two and makes the bulk of the island, while the inner 
is only half as long. Both reach an elevation of about rom. The 
island has emerged from the lake in comparatively recent time, and 
its history has been a simple one; moreover it is in all essentials the 
history of Isle Royale itself on a small scale. When the lake level 
was 3 m. higher than now there was a channel over the site of the 
bog area. At this time currents and waves were doubtless at work 
building bars across the channel mouths. With continued sub- 
