238 



DESCRIPTIVE CATALOGUE 



are several signs of wounding, there are series of traumatic 

 canals (PI. XX LI, fig. 2) and also zones of the parenchyma and 

 enlarged medullary ray-cells, which persist for a short distance 

 after the canals have died out. 



M'dullary rays are all uniseriate, rather inconspicuous, and 

 from 2 to 20 tracheids distant. They are low, the great 

 majority being from 2 to 5 cells in height (see text-fig. 68). 

 The ceils composing the rays are all alike, with somewhat 

 thickened walls. In the tangential section two or three small 

 leaf-traces can be seen coming out in a medullary ray. 



fh > 



Text-fig. 69. Todocarpoxylon Solmsi, sp. nor. Radial section, showing the 

 primary xylem, with protoxylenis, px., against the pith, p., and later- 

 formed, fine, scalariform elements merging into the ordinary tracheids 

 with bordered pits, ,r. No. V. 5427 d. 



DETAILS OF ELEMENTS. The pith is composed of three well- 

 marked types of cells. The majority of the ground-tissue cells are 

 circular in transverse section, increasing from small elements 

 round the primary wood to larger central cells. All these have 

 somewhat thickened walls and granular contents. Longitudinally 

 they are squarish, the external cells being a little more, but 

 not greatly, elongated (text-fig. 67, JP.). In transverse section, 



