248 PLANT ANATOMY. | 
tubers (Fig. 166) or in the Chinese galls (Fig. 91). In the 
Cinchona barks, the latex-tubes are distinguished by their 
considerable length, often also by a far greater diameter; in 
other cases, as in Fructus Papaveris and in Carica! (Fig. 167), 
they are developed as branched systems of canals. In this man- 
ner abundantly branched latex-tubes traverse definite layers 
of Radix Tarazaci (Figs. 163 to 165). Here the system of these 
tubes, without regard to the overground portions, is only de- 
veloped in the bark; in Lactuca virosa it extends also to the 
central parenchyma of the stem, together with all other parts 
of this plant. 
Fic. 166,—Cells from Tuber Jalape: containing laticiferous juice. 
One may accordingly speak of Jatex-cells and latex-vessels or 
tubes. The former are true cells, and, when formed already in 
the germinating plant, may often become very long, and, in- 
deed, absolutely branched, without being divided by transverse - 
walls, as for instance in the Urticacem, Euphorbiacee and 
_ Asclepiacer. The milk-tubes, on the contrary, are lysigenic* 
passages, that is, canals formed by the solution of the trans- 
1 The latex-tubes of the fig aré so striking that by means of them one 
May easily recognize an adulteration of coffee with ‘fig coffee” 
_ * Ado a dissolution, and yevvae I produce. 
