Structure, etc., of Epiphegus Virginiana. 369 



Stomata are frequently present along the stem epidermis. 

 They show a very simple structure; there are two short 

 swollen guard cells, with a slight orifice between. The entire 

 stoma projects out considerably beyond the level of the 

 stem surface. Similar simple stomata are abundant through- 

 out the plant, being found on stem, bracts, on the corolla, 

 even on the style, a quite rare occurrence in plants. This 

 abundance of stomata is a usual accompaniment of para- 

 sitism. The parasite takes in an enormous quantity of sap 

 from the host, as is evidenced by the rich deposit of starch 

 through all its tissues. So a great excess of water must be 

 brought into the plant, and a plentiful development of sto- 

 mata is needed in order to transpire off this excess. Since 

 leaves are present only in a rudimentary state, other organs 

 are compelled to assist in producing these stomatic struc- 

 tures. 



A noticeable fact in this connection is the rapidity with 

 which the plant withers after being severed from its connec- 

 tion with the beech root. This is no doubt due to the exces- 

 sive transpiration caused by the numerous stomata. 



The stem epidermis consists of a single row of narrow 

 cubical cells. A brown thickening is developed, especially 

 on the outer wall, but to some extent on the other walls. The 

 cortex cells are large and spherical, and are frequently sep- 

 arated by considerable spaces. Sometimes fine strands are 

 seen connecting two cell walls, across such intervening 

 spaces. The cells of the outer cortex are devoid of starch, 

 but starch is abundantly present in the deep layers of the 

 cortex and in the central pith region. Some starch grains 

 are simple spheres, others are of a complex structure, con- 

 sisting of a number of spherical segments fitting together. 

 The bundles lie in a ring around the pith. Between them 

 rays of the pith pass out to join the outer cortex, completely 

 isolating each bundle, and so giving to the stem an aspect 

 that is much looser and more primitive than that of the 

 typical dicotyledonous stem. This state of affairs is prob- 



