126 STUDIES IN ELECTRO-PHYSIOLOGY: 

 ANIMAL VEGETABLE 



Fig. 64. 



Network of capillary vessels of 

 the air-cells of the horse's lung. 

 (After Frey.) 



Fig. 65. 



Laticiferous vessels from a sec- 

 tion through the root of Scorzoncra 

 hispanica. (After Sachs.) 



LATICIFEROUS VESSELS. 



The resemblance of laticiferous to blood-vessels is 

 remarked by Sachs. He says : " The laticiferous vessels 

 themselves are always so narrow that they can never be 

 seen on a transverse section of the organ with the 

 unaided eye. The microscope, however, shows that 

 they may be of very different diameter in the same 

 plant. In the roots, shoot-axes, and nerves of the leaves, 

 run thicker tubes, from which thinner and yet thinner 

 ones arise. The substance of the walls of the tubes always 

 consists of soft cellulose, sometimes capable of swelling ; 

 they are never lignified, suberised, or otherwise essentially 

 altered by infiltration. One of the most prominent 

 characteristics of the laticiferous vessels is their continuity 

 throughout the whole plant, or at any rate over wide areas. 

 This may obviously, even if not in every point, be closely 

 compared with the vascular system of an animal. . . . 



