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absence of bast tissue, and the presence of only bordered pores in 
the libriform cells. This occurrence of only bordered pores in the 
libriform has been found by Dr. Gregory to be a characteristic 
common to the orders Empetracee and Ericacee—a fact which 
may bear upon the question of relationship between them. 
This examination of the anatomy of the stem and leaf of the 
two species brings us to the question, What does it indicate re- 
garding the relationship between Corema Conradii and Corema 
alva? Considering only the anatomy of the two stems, it leads 
decidedly to the opinion that they are species of the same genus. 
This relationship is not so strongly indicated, however, by the 
character of the leaves. A 
Taking alva as the type of the genus, the variations from the 
type shown in the Conradii leaf would indicate an adaptation of 
that plant to a changed environment rather than an original gen- 
eric difference. This plant, C. Conradii, has apparently adapted 
itself to a climate subject to drought and extremes of heat and 
cold. This is first shown by the thickening of the leaf, whereby 
the working tissues are more compactly arranged and a smaller 
Surface isexposed. To provide against long continued drought, 
there is an arrangement similar to that found on leaves which are 
known to need protection from excessive evaporation. The long 
hairs before referred to, which are found only on the very edges 
of the Conradj leaf, interlace, forming a felt-like mass, with only 
capillary spaces through which the lower surface of the leaf has 
communication with the air. This regulates the amount of evap- 
oration from the stomata by retarding the escape of moisture from 
the channel inside, while at the same time, by retaining the heat 
Siven off, it protects it against the cold. - 
On the other hand, this arrangement of hairs, which prevents 
€vaporation and raises the temperature of the leaf, hinders the free 
interchange of gases. This, again, is remedied by the raised 
Stomata. If the stomata were sunken, or even level with the epi- 
dermis, it would be difficult to effect the proper circulation inside | 
the tissues. Hence the development of the raised stomata, which, 
by their form, allow a freer passage of air in and out. Further- 
More, there is a great increase in the number of stomata over a 
those on the ala leaf. 
