CHAP. I. 
PITTED TISSUE. 
21 
the sap is observable. In those Schleiden has remarked (and 
my own observations coincide with his) that all the currents 
proceed from the Cytoblast and return to it. 
Sect. II. Of Pitted Tissue^ or Bothrenchyma,'^ 
This, which has had a variety of names, {Tubes poreizx, 
Vaisseaux en chapelet, Tubes corpusculiferes, Vasiform Tis- 
sue, Dotted Ducts,) consists of tubes, often of considerable 
size, appearing when viewed by transmitted light as if 
riddled full of holes. • Upon a more accurate inspection, 
however, it is found to receive that appearance from its sides 
being filled with little pits sunk in the thickness of the lining. 
(See Plate II. fig. 2.) Of this there are two kinds. 
1. Articulated Bothrenehyma. — This is very common in 
wood. The holes which are so evident to the naked eye, in 
a transverse section of the oak or the vine, are its mouths ; 
and the large openings in the ends of the woody bundles of 
Monocotyledonous stems, as in the Cane, are also almost 
always caused by the section of it. The stems of Arundo 
Donax, or of any larger grass, is an excellent subject for 
seeking it in ; it can be readily extracted from them when 
boiled. It is composed of truncated cylinders, placed one 
upon the other, and so forming a long cylinder, which be- 
* BoOpoCy a little pit. 
c 3 
