304 COMPOSITE ORGANS. CHAP. II; 



Saussure the elder, whose observations on the 

 epidermis are the next in order of time, and who 

 studied it chiefly in the leaves and petals of Jes- 

 samine and Fox-glove, describes it as constituting 

 a bark composed of two layers ; the interior layer 

 consisting of a net-work, which he calls the cortical 

 net-work, interspersed with a multiplicity of what 

 he calls cortical glands ; and the exterior layer con- 

 sisting of a fine and transparent membrane which 

 he regards as the true epidermis, capable of being 

 partly detached, but totally destitute of organiza- 

 tion. The glands he describes as being small and 

 oblong or circular bodies, encompassed by a fine 

 thread or fibre, not immediately attached to them, 

 but separated by a narrow interval, and communi- 

 cating with the cortical net-work, as well as being 



O 7 O 



in some plants discoverable with the assistance of 

 a good glass, even through the exterior layer of 

 the epidermis, under the appearance of white and 

 transparent spots. Their mean diameter was about 

 the eightieth part of a line. They were more nu- 

 merous on the upper surface than on the under 

 surface of the leaf; but were not to be met with in 

 the epidermis of the petals, which seemed however 

 to be furnished with organs somewhat analogous; 

 namely, small vesicles of a conical form, emerging 

 from the surface, and perhaps giving colour to the 

 corolla.* 



Hedwig, who was led to the investigation of the 

 subject, from a wish to repeat some experiments 

 * Observ. sur 1'Ecorce de Feuilles, &c. 



