THE TISSUES OE PLANTS. 



27 



" Cow-tree " of South America, the latex is nutritious, 

 and is used by the natives as a wholesome drink. 



FlQ. 16. 



Fig. 17. 



Fig. 16.— Milk-tubes from a Spurge (Euphorbia). A, moderately mag- 

 nified ; B, more highly magnified, and showing the hone-shaped starch- 

 grains. 



Fig. 17.— Milk-vessels of a Composite (Soorzonera). A, a transverse sec- 

 tion of the root ; B, the same more highly magnified. 



Practical Studies. — In studying milk-tissue it is necessary first to 



