143 



PLANT ANATOMY. 



Fig. 56.— Croas section of Radial bundle in root of Veratum viride, k, endodermis 

 portions, s. sieve portions. (Tschirch). 



largely of Albuminoids. These often 

 form by deposit upon the upper surface 

 of the sieve a callous growth which is 

 apt to appear in auUimn and winter, and 

 to stop Tip the openings of the sieve. 

 This; may be redissolved in the spring, 

 or, in some cases, it may continue until 

 it obliterates the sieve tubes entirely, ns 

 is the case In Radix Glycyrrhiza. 



(b) The Cambiform Cells are exceed- 

 ingly thin-wnlled, elongated cells with 

 sharpened ends. They closely resemble 

 Cambium cell, and are filled with proto- 

 plasmic contents. Their walls have no 

 traces of pores. 



(c) Accompanying Cells (Geleit Zellen) 

 are cells accompanying the sieve tubes. 

 They are seen to best advantage on the 

 cross section of the bundle, where they 

 appear more or less quadrangular, with 



small lumen and very thin walls. They 

 transmit protoplasmic substances au(3 

 are connected ofttimes by pores with the 

 sieve tubes. 



In specimens of dried drugs it is al- 

 most impossible to distinguish the accom- 

 panying cells or the cambiform cells, as 

 they are so delicate. 



3. Conducting Parenchyma. As in 

 the Hadrom parenchymatic cells were 

 found taking on the function of conduct- 

 ing water, so in the Leptom portion ot 

 the bundle there are numerous paren- 

 chymatic cells which conduct plastic sub- 

 stances. The prominently marked starch 

 sheath of many Monocotyledons and 

 young Dicotyledons belongs to this group 

 of tissues. The parenchymatic tissues 

 of the phloem are important agents in 

 carrying on this function. 



