=~ 7 
Researches into the Anatomy of Plants. 473 
V. Pores of the Epidermis, the Glandules, and the Down of | 
Plants. 
The pores of the epidermis are formed by a small slit, 
sometimes open and sometimes close. 
1. These pores exist in all the phanerogamous plants, 
except the Naiades which are almost entirely under water. 
2. They are wanting in the cryptogamia, the ferns ex- 
cepted, and the apophysis of the capsules in the mosses. 
3. The roots of piants never have any. 
4. They are found in the young and green stalks, when 
not under water. 
5. The leaves are generally furnished with them,sometimes 
on the lower side, and sometimes on both. The leaves of 
the aquatics which float on the water, have pores on the 
upper and none on the lower surface. 
6. The bractez are furnished with them, particularly 
those which are green: they are wanting in the dry which 
are called scarious bractee. 
7. The external coat of the calyx has them. 
8. The parts of the flower called the corolla, and which 
M. Jussieu reckons among the calices, have them very fre-. 
quently which proves their analogy. 
9. The corolla, the stamina, and the pistils almost ,al- 
ways want them. Some very large corolle only, for in- 
stance, those of the Stapelia, have them. 
10. The fruit has them when it is green, in the state of 
maturity it never has. 
I shall add a fact, which appears to me to he new. I 
have seen in some grasses two kinds of pores united at the 
same part of a different size. Iu the epidermis of the leaves 
of rye represented in Pl. IL. fig. 11. we see very large pores 
at a, and very small ones at 6. I could wish this experi- 
ment to be repeated, for the pores at ) are so small that I 
may have been mistaken. 
Some naturalists are of opinion that the organs serve the 
purpose of evaporation while others regard them as adapted 
to attract humidity. Iam of the former opinion for the 
Jatter is not warranted by my experiments. 
I am convinced that the pores serve the purposes of se- 
cretion, or rather of excretion to the plant. A dark-co- 
Joured foreign matter frequently fills up the crevices of these 
organs. In the pines for instance, it looks like small round 
worms; but when the leaves are dipped m boiling water the 
pores immediately become distinct. 
The glandules haye similar functions to perform. Their 
structure 
