28] 



CHAPTER II. THE TISSUES. 



instance, the tannin-sacs of the Hop ; the sacs containing raphides- 

 and mucilage in Tradescantia and many other Monocotyledons - 

 the gum-resin sacs (" vesicular vessels ") of the bulb-scales of the 

 Onion ; the sacs containing crystals of calcium oxalate in the 

 cortex of many woody Dicotyledons ; the sacs, containing milky 

 juice or latex (com- 

 monly gum -resin) in 

 the Sycamore, the Con- 

 volvulaceae, and the 

 Sapotacese (especially 

 in Isonandra Gutta, 

 the latex of which con- 

 stitutes gutta-percha). 



(d) Laticiferous ves- 

 sels. These structures 

 resemble the sacs con- 

 taining milky juice 

 (latex) in the nature of 

 their contents, and 

 differ from them struc- 

 turally only in that the 

 walls between adjacent 

 cells have become ab- 

 sorbed, thus forming 

 syncytes (p. 64). 



In the simplest case, 

 the laticiferous vessel 

 merely consists of a 

 longitudinal row of 

 cells whose transverse 

 septa have become ab- 

 sorbed, thus forming a 

 syncyte of the nature 

 of a vessel. When two 

 such vessels are in con- 



, , 1 , I-, ,, ,, FIG. 80. Laticiferous vessels from the cortex of 



terally, tfi the root of Scorzonera hi epan i ca , tangential section : A 



walls are absorbed at slightly magnified; B & small portion highly magni- 



the point of junction, fled ' (After *"*> 



and in this way a continuous system of laticiferous vessels is formed. 

 This occurs in the greater Celandine (Chelidonium majus}, and in 

 the Banana (Musa) where, however, the latex is not milky. 



