486 BOTANICAL GAZETTE [JUNE 
twigs of Larix exhibited virtually as high a rate of conduction, 
especially from colder solutions. 
13. From the experimentation it appears that the rate of con- 
duction is ample to the needs of these plants for temperatures 
above —15° (and probably above — 20°). 
14. The transpiration of all plants experimented with in summer 
was very decidedly greater than in winter. This was most marked 
in deciduous species and least so in evergreen species. 
15. Under summer conditions, hydrophytes exhibited the 
highest transpiration per unit area of leaf surface. In general, 
herbaceous plants transpired at a higher rate than shrubs. The 
more hydrophytic swamp shrubs transpired at a higher rate than 
the typical bog shrubs. The evergreen shrubs transpired at a very 
distinctly lower rate than the deciduous ones. Among the bog 
trees the lowest rates occurred in the evergreen species. The 
rate of the deciduous conifer Larix laricina was noticeably higher 
than that of the deciduous broad leaf tree Acer rubrum, and was 
decidedly higher than that of the evergreen conifer Picea mariana. 
16. The rate of conduction under summer conditions was very 
high in comparison to that under winter conditions. This was 
less noticeable in the evergreen ericads than in other plants. The 
summer rate in Chamaedaphne was but 10-20 times that of the 
winter rate. The maximum rate obtained under conditions of 
experimentation which were not extreme was 23 cm. per hour in an 
evergreen ericad, while rates above 100 cm. per hour were fre- 
quently found in other shrubs and in herbaceous plants. An 
evergreen bog tree, Picea mariana, exhibited a distinctly lower rate 
of conduction than deciduous trees whether conifer or hardwood. 
17. In the case of peat bog plants in nature, light (particularly 
sunlight) seems to be the effective factor in causing stomatal 
movements. Stomatal movements, while effective regulators of 
transpiration when they occur, do not appear so closely to regulate 
transpiration of peat bog plants as the evaporating power of the air. 
18. In view of the fact that exposure to the very extreme 
summer conditions in 1911 and rtg12 did not affect the vitality of 
the evergreen ericads, that neither did the average winter of 1910- 
1911, with its scanty snow covering during the coldest weather, 
