of Lathraa Sguamaria,^c. 413 



in this figure) runs along the whole underside of the leaf be- 

 neath the course of the dotted line a. b. of Tab. XXIII. 

 Fig. 6 ; and communicates, by means of an oblong narrow 

 orifice (Fig 9. c), with the bottom of each of the perpendicular 

 leaf-cells. This appearance may be best detected in a very thin 

 longitudinal section of the leaf placed under the microscope ; 

 and though the inner curvature of the leaf d. will sometimes 

 adhere to the leafstalk e, and close the aperture, the application 

 of a needle or bristle will immediately discover it. The cuticle 

 of the leaves is destitute of pores on both its surfaces*. When 

 highly magnified, it appears to be traversed by an irregular net- 

 work of veins, the reticulations a little prominent, and connected 

 by a transparent but strictly imperforate membrane. 



Keeping in view this very curious and singular structure, I 

 think its oeconomy cannot be misunderstood ; viz. that the 

 squamae or scales of the subterranean stem are real leaves, and 

 that the prominent glandular papillae of their interior cells 

 perform the office of true cuticular absorbents. Under ordinary 

 circumstances, leaves freely exposed to the action of the air and 

 of light, and provided with a porous cuticle, receive carbonic 

 acid gas into the cells of their parenchyma, where the oxygen is 

 separated and thrown off, and the carbon assimilated with the 

 hydrogen imbibed by the roots. But in the case of the Latfircea, 

 where they are destined to perform their functions, not only in 

 the dark, but buried in the earth, such an arrangement would 

 have been inexpedient; it is therefore substituted by another, 



* So is the cuticle of the flower-stem, the individual flower-stalks, the calyx, and 

 both surfaces of the bracteas. The copious woolly hair on the flower-stem and calyx, 

 when highly magnified, appears jointed like a bamboo cane, and tipped with a globular 

 or oval summit; but I cannot ascertain whether they are perforated. The bracteas 

 have neither the internal cells nor the bladders of the true leaves ; but there are often 

 several at the base of the flower-stem, of an intermediate character, being partly succu- 

 lent and chambered like the latter, and partly thin and solid like the former. 



admirably 



