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1896] BRIEFER ARTICLES 405 
The stereome (S¢, in fg. 5) is well developed in this genus, and 
forms groups above and below each mestome bundle. On the inferior 
face of the leaf the stereome is sometimes bordering immediately on 
the parenchyma sheath, but is also seen to be separated from this 
either by the adjoining mesophyll or by colorless parenchyma. The 
stereome of the superior face is constantly separated from the paren- 
chyma sheath by one to three cells of colorless parenchyma. The 
stereome has attained its highest development, however, along the 
margins of the blade (fg. z). We see here an enormous group of this 
tissue connecting the two faces of the leaf, and by this character 
Amphicarpum is readily distinguished from any of the other genera 
which we have previously examined and described. 
The mesophyll occupies quite an extensive part of the leaf blade, 
and forms usually separate groups between the mestome bundles, 
excepting where it passes uninterruptedly underneath these, between 
the stereome and the parenchyma sheath. It forms a compact tissue 
with the cells radiating from the mestome bundles, and no lacunes 
are observable. The colorless parenchyma has already been touched 
upon above, and we have seen it developed as a closed parenchyma 
sheath and as small groups or single cells between the stereome and 
the mestome bundles. As shown in /ig. /, it has attained its highest 
development on the superior part of the leaf. 
AMPHICARPUM PuRsHII.—The epidermis of both faces of the leaf 
shows very nearly the same structure as we have described for A. 
Floridanum, but we note the following differences: The bulliform 
cells are here equally well developed on both faces (Jg. ©); epidermal 
€xpansions as very long unicellular hairs are frequent on both faces, 
and are especially common in the bulliform strata. The thorn shaped 
€xpansions in this species seem to be most common in the stomatifer- 
ous strata, near the bulliform cells. The mestome bundles do not 
seem to differ from those of the other species, and the same is true of 
the mesophyll and the stereome. The colorless parenchyma is less 
developed on the superior face than we have seen in A. Floridanum. 
Fig. 6 represents a transverse section of the median part of the leaf, 
and we see here only one single cell of colorless parenchyma above 
the parenchyma sheath, while below this the sheath borders immedi- 
ately on the stereome. : : 
In comparing the leaf structure of these two species of Amphi- 
“pum, the principal anatomical differences are as follows : 
