1905] BRIEFER ARTICLES 225 
is to be found in Ulmus, the serrations of whose leaves become functional 
when the latter are still very small, or about the time they are emerging 
from the bud scales. It is not necessary to cut sections to observe this 
phenomenon, for the leaf margins are of a deep green color, which con- 
trasts strongly with the pale yellowish-green of the remaining portion 
(jig. 1). The serrations appear slightly swollen as though the leaf were 
thicker in this region than elsewhere. The color contrast remains for a 
considerable time, or until the leaf has nearly reached its full size. 
It requires but a section of a young Ulmus leaf to prove that the ser- 
tations really have fully developed spongy parenchyma and functional 
stomata, while adjacent and other portions of the leaf consist of compact 
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: Fic. 2.—Cross-section of a leaf at the margin; the spongy parenchyma on the 
Tight is readily distinguishable from the compact embryonic tissue on the left. 
"sue. Th fig. 2 it will be seen that in the right or marginal portion of the 
“ection the air spaces are such as would be found in any ordinary mature 
Mesophytic leaf; while on the left of the section, which lies toward the mid- 
te a will be seen regular rows of cells compactly arranged and evi- 
oa embryonic condition. It will also be noticed that the marginal 
Portion is thicker, in consequence of the development of air spaces. 
2 a 0 ae that other instances of precursory leaf serrations will be 
» M Tact one other was found by the writer, but it was not so well 
ll case as that of Ulmus.—Freperick H. Brix1nes, Louisiana 
wersity, Baton Rouge, La. 
THE EFFECT OF DIFFERENT SOILS ON THE DEVELOPMENT 
OF THE CARNATION RUST. 
an = ideas are held in regard to the rusting of plants, especially 
them srains, and to a limited extent asparagus, carnations, and chrysan- 
The conditions which favor the rusting of such plants as the 
Most part d the chrysanthemum, plants grown in the greenhouse for the 
ing of f 1 are probably better understood than those which favor the rust- 
eld crops. However, the conditions that would tend to bring 
