118 PRACTICAL BOTANY 



LATICIFEROUS TISSUES 



The material for the study of these tissues should be 

 prepared by treatment with alcohol to coagulate the 

 latex. Care should be taken to place the material in 

 alcohol directly it is cut, or at least the cut surfaces 

 should be wetted with alcohol so as to check the flow 

 of latex from them. If the latex be allowed to escape, the 

 laticiferous tissues are emptied, and are then much less 

 easily traced than when they are full. The best method 

 is perhaps to preserve the whole plant without injury 

 in alcohol, in which case the latex will not be lost 

 at all. 



Draw from a piece of the fresh stem of Euphorbia 

 a drop of latex upon a slide : examine it quickly under 

 the microscope, and observe the fluid is at first almost 

 uniformly milky, but that in a short time a coagulum 

 separates in irregular masses from the more transparent 

 fluid. The coagulation is effected more completely 

 and rapidly on addition of a drop of alcohol. 



i. Laticiferous Vessels. 



I. Cut tangential sections from the phloem of the root 

 of the Dandelion (Taraxacum officinale), mount in potash 

 and glycerine, and warm ; examine under a low power. 



The main constituents of the tissues are parenchy- 



