LATEX-CELLS 



339 



Fungus, forcing themselves between the neighbouring cells and pene- 

 trating into the growing points of shoot and root. Since latex-cells 

 never arise dc novo during the subsequent development of the plant, the 

 entire laticiferous system of the plant-body is derived from the small 

 number of initials which become differentiated in the embryo. If 

 subsequent additions to the system are required for instance, in connec- 

 tion with the formation of adventitious buds the existing latex-tubes 

 simply give rise to new branches at appropriate points according to 



Fig. 137. 



Portions of latex-tubes dissected out. A. Ultimate ramifications of a latex-cell 

 from a young leaf of Euphorbia Myrsinites. B. Anastomosing latex-vessels from 

 the cortex of the root of Scorzonera hispanica. X120. B. after Unger. 



Chauveaud, the " secondary " latex-tubes which appear among the 

 products of cambial activity are produced in the same way. The 

 differentiation of latex-tube initials thus appears to cease altogether at 

 an early stage of embryonic development. 



In considering the functions of latex-tubes, we may once more begin 

 with a discussion of the anatomical data from the physiological point of 

 view. If the course of the latex-tubes be carefully traced through root 

 or stem, petiole or mid-rib, it will be found that these structures every- 

 where maintain close relations both with the conducting parenchyma 

 and with the leptome-strands, being either opposed to, or embedded in, 

 these conducting tissues. This circumstance in itself strongly suggests 



