LATEX-TUBES. 249 
verse walls. With these are to be classed the tubes of the Cicho- 
riacee (Taraxacum) and those of the Papaveracee and Cam- 
panulacee, 
If a resorption of the transverse walls does not take place, but 
the short latex-cells lie in rows over each other, lactescent lines 
of cells are produced, as for instance, in the Convolvulaces 
(Tuber Jalape, Fig. 166); gutta percha (mostly from Dichopsis 
Gutta Bentham et Hooker) also occurs in such lines of cells 
containing laticiferous juice. 
The contents of the latex-tubes is a mixture of very variable 
composition.’ Besides the more commonly distributed substances, 
v = 
Fig. 167.—Latex-tubes of the fig; tangential section throngh the more central layer. 
1, tubes; 4, rosette of crystals of calcium oxalate; v, vascular bundle. 
such as salts (calcium malate), starch and protein bodies, very 
many, if not all, laticiferous juices contain caoutchouc. Pe- 
culiar bitter principles.and alkaloids (as in opium) also occur in 
them, and some laticiferous juices are therefore medicinally 
valuable (opium, euphorbium, lactucarium). In the latex of 
species of Huphorbia is found the indifferent, crystallizable 
euphorbon. The milky juices which here come under considera- 
tion are white in their fresh condition. 
Caoutchoue appears in the laticiferous juices in the form of 
globules, which swell in volatile oils, and are not changed by 
1 Compare among others S. Dietz, ‘‘ Beitrag zur Kenntniss des Milch- 
saftes der Pflanzen,” Botan. Centralb., 1883, xvi., p. 133. : 
