Dr. Wiltshire's Contributions to Structural Botany. 5 



distinct from that in which Schleiden has shown fibre without 

 membrane arises. It appears to me to have its origin from 

 primordial membrane alone, and that the formation of a second- 

 ary layer, — a spiroidal fibrous one, — has nothing to do with it. 

 The layer of tissue at first was a common cellular one, com- 

 posed of several parallel series of square-shaped cells, having 

 rather wide intercellular spaces between them : as the increase 

 of development ensued, the primary membrane forming the 

 superior and posterior walls of the cells became absorbed, 

 leaving only the lateral ones, which thus formed a series of 

 membranous walls to a continuous and inosculating series of 

 intercellular spaces : the edges of these walls finally becoming 

 connected or grown together, and the intercellular spaces 

 filled with colouring matter, an apparently fibrous tubular 

 layer is the result. 



In Bromelia nudicaulis it has been remarked by Dr. Lind- 

 ley, that the membrane of the cuticle breaks into little teeth 

 of nearly equal width when torn ; I have observed the same 

 circumstance to occur in Tillandsia usneoides. 



6. — In the spirally-twisted fruit-vessel of Loasa lateritia com- 

 mon cellular tissue is displaced by another structure, in order 

 to admit of that peculiar direction which the pericarp assumes. 

 This structure consists of elongated cells, closely approaching 

 to, or even apparently identical with, one portion of the woody 

 tissue of the stem, and which are marked longitudinally by a 

 single row of dots or pores exactly like those on the ducts of 

 the vascular system of the plant : the fibres of the different 

 layers cross each other obliquely, so that when two layers are 

 examined under the microscope the structure is netted, and be- 

 tween each mesh a single pore is seen. The seeds are enveloped 

 in a rather lax covering of membrane, which is traversed by 

 anastomosing tubular fibres of a bright brown colour, and 

 which at the edges of the seed becomes expanded into a wing. 



7. — Meyen is right in affirming what has been denied by 

 Korthals, namely, that the glandular hairs of Drosera contain 

 spiral structure. In the centre of the hair I have generally 

 succeeded in unrolling a spiral vessel; this by Meyen is said 

 to be single, but in many hairs I have found more than one. 

 Korthals is also wrong in his description of the glandular 

 head : I have never been able to discover any hollow there ; 

 the centre is in fact of a dense consistency, formed of elon- 

 gated cellules, assuming in the mass an oval shape. The 

 whole hair is enveloped by a layer of tissue, which is derived 

 from the epidermis of the leaf, and which in old hairs becomes 

 loose and lax, like a sheath. The cells containing the colour- 

 ing matter are elongated, fusiform, or club-shaped. 



