Ch. IV, 3] 



ANATOMY OF STEMS 



129 



Fig. 85. — The cellular anatomy, in corresponding cross and longitudina? 

 sections, of a young stem of Aristolochia Sipho, a twining vine ; X 50. 

 In the center, the pith ; next three fibro-vas 

 cular bundles, showing the xylem with 

 ducts, the rectangular nucleate cells of 

 the cambium, and the phloem, 

 marked by sieve-plates and nu- 

 cleate cells; next the sclerenchyma 

 ring, with the starch sheath 

 just outside ; then the cor- 

 tex, consisting of chlo- 

 renchyma and collen- 

 chyma ; and finally 

 the epidermis. 



