52 



THE ELEMENTARY STRUCTURE .OF PLANTS. 



abrupt extremities. Even the pointed overlapping ends of two 

 contiguous ducts frequently communicate at maturity, by the ob- 

 literation of the membrane between the coils of the fibre. The 

 turns of the spiral fibre are more commonly close, as in Fig. 48, a; 

 but they are often separated, even widely, as if the thread had 

 been extended by the elongation of the cell after the spiral deposi- 

 tion had been formed. Fig. 48 exhibits several degrees of this, in 

 different vessels of the very same bundle. 



62. Interlaced Filmlliform Tissue, This is quite as distinct from 

 ordinary cellular tissue, and as worthy of a special name, as is 

 any sort of the so-called vascular tissue of plants. It is the more 

 worthy of notice from its near resemblance to ordinary forms of 

 animal tissue. It consists of very long and much attenuated, sim- 

 ple or branching, fibre-like cells, or strings of cells, inextricably 

 entangled or interwoven without order, so as to make up a loose, 

 fibrous tissue. It is principally met with in Fungi, Moulds, &c., 

 where the cells are extremely soft and destructible ; and in Li- 

 chens (Fig. 15), where it is dry and much firmer. 



63. LaticiferoilS Tissue, ( Vessels of the Latex or Milky Juice. 

 Cinencliyma of Morren and Lindley.) This, the only remaining 

 kind of vegetable tissue, is of an ambiguous character. It consists 

 of long and irregularly branching tubes or passages, lying in no 

 definite position with respect to other tissue, and when young of 

 such extreme tenuity (their average diameter being less than the 



fourteen-hundredth of an 

 inch) and transparency that 

 they are hardly visible, even 

 under powerful microscopes, 

 except by particular manip- 

 ulation. But their older 

 trunks are much larger than 

 this, when gorged with the 

 milky or other special juices 

 which it is their office to 

 contain, and when their 



sides are thickened by the deposition of such matters. Another 

 peculiarity is, that they anastomose or inosculate, forming a sort of 

 network by the union of their branches, like the veins of animals, 



FIG. 49. Vessels of the latex, ramifying among cellular tissue, in the Dandelion ; and 50, 

 older and larger vessels from the same plant ; all highly magnified. 



