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PHILOSOPHICAL NOTES OX 



At p. 82a of the Siime work a glandular hair is given from the 

 tooth of the stipule of Viola tricolor. " At the apex of each tooth 



there is a beautiful egg-shaped gland." "It consists 



of two or more rows of elongated cells forming a core, upon which 

 a single layer of cells is placed, arranged perpendicularly to the 

 surface, and elongated in this direction." Fig. 118 shows that, in 

 addition to the secreting epidermal cells, there is a core of cells 

 which is continuous with the inner structures of the stipule, 

 although it is a glandular hair. 



These superficial cells are a continuation of the epidermal cells. 

 Morphologically, they are cells of the epidermis, like trichomes, 

 although functionally they are secreting or excreting cells, the 

 secretion consisting of slime and resin. 



Fiff 118. Tooth-gland of stipule of Viola tricolor (Strasburger and 

 Hillhouse, Fig. 36rt) : («) inner structure of stipule. 



Prof. Henslow lays stress on the fact that the fibro-vascular 

 cord of the Drosera leaf branches into the tentacles, in order to 

 prove tliat they are not trichomes. Let us, however, take another 

 important organ — the sporangium of ferns, which is not considered 

 as a trichome, Fig. 120. It is evidently a specialized trichome, as 

 its stem is only cellular, and the inner tissues of the leaf do not 

 branch into it, as in iho Drosera tentacle and stipule gland of 



