324 



MANUAL OF BOTANY 



These resemble laticiferous vessels in one particular, as they 

 contain latex, in which are generally true raphides ; on the other 



Fig. 699. 



Fig. 700. 



Fi(i. 699. DeTelopment of lysigenous gland in stem of Hypericiwi. The 

 four figures represent successive stages, x 250. 



hand, they are unbranched and much like sieve tubes in form, 

 consisting as they do of long, broad cells with sieve-like septa. 

 They were first noticed by Hanstein 

 in the scales of the bulb of 

 Allium. 



Glandular Tissue. — This has a 

 much more limited distribution than 

 the laticiferous tissue. It consists 

 of single cells or of masses of cells 

 of various shapes, sometimes long 

 columns, sometimes ovoid or 

 rounded collections. Thecellswhich 

 compose these masses are dis- 

 tinguished by their power of forming 

 peculiar, generally aromatic, sub- 

 stances, which either remain stored 

 in the cells or are passed out into 

 intercellular spaces or cavities or to 

 the exterior. 

 The cells are usually parenchymatous and filled with very 

 granular protoplasm. The collections of such cells are commonly 

 called glands, a name which is also applied to the cavities con- 



Fi'J- 



700. Scbizogenous resin- 

 duct in the young stem of the 

 Ivy {Hedtira helix)^ transverse 

 section ( X 400). a. An early; 

 B, a later, stage, f/. The resin- 

 ducts. 



