of Lathraa Squamaria, SfC. 411 



parasitic on roots, it is copiously supplied with true leaves, while 

 it shares, in common with them, the appearance indicative of the 

 want of those organs. Assuming for the present that the tooth- 

 like scales of the subterraneous stem are really leaves, the appa- 

 rent anomaly will be reconciled by reflecting that their functions 

 are necessarily performed in the total absence of light, that 

 essential agent in the production of the common livery of the 

 vegetable kingdom. Neither is their cuticle perforated by any 

 pores. In order to ascertain if light would produce any change, 

 on the 20th of November last I carefully laid them bare and 

 washed away the soil ; but after having been as much exposed 

 as their gloomy situation would admit till the middle of January, 

 they had not acquired the slightest approach to a green colour, 

 nor any absorbing pores. Frost now set in ; and on again 

 examining them on the 5th of February, I found the uncovered 

 parts blackened and destroyed by this unnatural exposure. A 

 head of flowers has since shot up within two inches of the spot, 

 without any change in its natural appearance. 



The general shape and character of the leaves, though they vary 

 considerably in detail, are known to most botanists, and may be 

 understood by reference to Tab. XXII. Fig. 2. & 3, and Tab. 

 XXIII. Fig. 6. 7. & 8. If their outer or convex surface be viewed 

 attentively by the naked eye, especially those on the newly formed 

 branches, a number of longitudinal parallel striae, or tubes, may 

 be observed under the cuticle, whiter and more diaphanous than 

 the contiguous parts, but having no apparent orifice or external 

 communication. On dissecting the leaf, these are found to be so 

 many hollow cells or chambers imbedded within its solid succu- 

 lent substance ; and varying in number from six to twelve accord- 

 ing to the size of the leaf. A lens of moderate power shows their 

 interior surface to consist of a variety of irregular corrugations 

 or tortuous ridges, which increase the superficial area very con- 

 siderably. 



