118 



some cells and the large clusters of needle-like raphides in others 

 which are scattered through the parenchyma, being more numer- 

 ous near the epidermis than elsewhere (Fig. 2, r). No trace of 

 starch could be found. The fibro-vascular bundles consist of a 

 few spirally thickened tracheids and some small proteid-carrying 

 elements. 



The epidermal cells of Hexalectris are evidently accommodated 

 directly to the absorption of water and food-stuffs, for as Green 

 suggests as to the hairless roots of Neottia, " lying in a bed of 

 humus, they do not need such close contact with continually 

 fresh particles of soil as do the roots of the ordinary phanerogam, 

 hence short-lived hairs are unnecessary." * The epidermal cells 

 with their reticulate thickenings may serve, like the velamen cells 

 of the roots of epiphytic orchids, both as a sponge to absorb 

 moisture and also as a protective organ to prevent its escape. 

 The presence of raphides, which are insoluble in water, so near 

 the epidermis may have something to do with the breaking down 

 of the humus compounds which are very slightly soluble in 

 water. The addition of a small quantity of acid causes the 

 raphides to dissolve and thus an acid may make them available 

 to attack the humus. Such crystals are mentioned in the stems 

 or roots of other plants which absorb organic matter, as in 

 Plioradendron villosum by Cannon, f in Grammatopliyllum spccio- 

 sum by Groom, % and in Ceplialanthcra Orcgana, by MacDougal.§ 

 Pfeffer || has shown by experiment that some especial apparatus 

 is necessary for making humus available to seed-plants. A few 

 septate filaments of a fungus are found upon the rhizome, scape 

 and seed-capsule of Hexalectris, but it cannot be seen to enter 

 the cells at any point nor to come into close contact with them, 

 besides it is not sufficient in quantity to perform the practical 

 work of a symbiont, though its presence may serve to retain 

 moisture near to the epidermal cells. Its presence on the seed- 

 capsule suggests a possible example of Bernard's theory that a 



-• Intr. to Ve^. Phys. 199. 1899. 



f Bull. Torrey Club, 28 : 377. 1901. 



jAnn. Hot. 7: 146. 1893. 



\ Bull. Torrey Club, 26 : 514. 1899. 



|| Pfeffer, Phys. of Plants, trans, by Ewart, 1 : 367. 1899. 



