290 



MOSSES AND FERNS 



CHAl 



the earlier literature upon the anatomy of the Marattiacese. In 

 the stem of Angioptcris there is a reticulate vascular cylinder 

 like that of Opiiioglossiim, but within this are three or four 

 similar concentrically arranged "meshed zones," and a single 

 central strand. In the specimen examined by Miss Shove the 

 stem was oblique, and the meshes of the vascular cylinders were 

 much closer upon the dorsal than upon the ventral side. 



The majority of the roots originate from the inner zones, 

 but thev may also arise from the outer ones. The leaf-traces 

 all come from the outer zone — at least such w^as the case in the 

 specimen studied by Miss Shove. It is stated that Mettenius 

 (3), found that the leaves also received strands from the second 

 vascular zone. The concentric vascular cylinders are connected 

 by branches ("compensating segments"), wdiich pass out to 



Fig. 162. — Dancea alata. A, Transverse section of vascular bundle of the petiole, X17S', 

 X, tracheary tissue; t, tannin cells. B, Cross-section of a mucilage duct, Xi75- 



the gaps formed by the departure of the leaf-traces. Marattia 

 (Kiihn (2)), closely resembles Angioptcris in its stem struc- 

 ture, but it has but two vascular cylinders outside the central 

 strand, while Kanlfussia has but a single one. The bundles, 

 are, according to Holle ( (2), p. 217) concentric, but the phloem 

 more strongly developed upon the outer side. 



The thick petioles of the full-grown leaves are traversed by 

 very numerous vascular bundles, which at the base give off 

 branches that supply the thick stipules within which they 

 branch and anastomose to form a network. These bundles in 

 Angioptcris (Fig. 161, A) are arranged in several circles, or 

 according to I)e \'riese ( i ) and Harting, the central ones form 

 a spiral. In the rachis of the last divisions of the leaves, how- 



