MALE FERN. SPOROPHORE. 191 



glycerine or glycerine jelly, others (2) in acid aniline 

 sulphate, others (3) in Schulze's solution. Examine 

 under a low power, and observe successively the fol- 

 lowing tissues, starting from the periphery of the stem : 



a. An Epidermis, consisting of a single, somewhat 

 irregular and ill-defined layer of cells, with dark brown 

 outer walls : their arrangement is disturbed at the 

 point of insertion of the scaly hairs, which appear as 

 plates of cells, one layer in thickness, rising obliquely 

 from the epidermis. Beneath this is 



1. The Ground tissue, which is differentiated as 



i. An outer narrow band of tissue, with rather thick, 

 colourless, pitted walls, and cell-contents with much 

 starch : there are no intercellular spaces. 



ii. A band of Sclerenchyma with thick, yellow, 

 lignified, obviously stratified, and pitted walls, cell- 

 contents as in (i), and no intercellular spaces. This 

 merges gradually into 



iii. The bulky central mass of ground-tissue, in 

 which the vascular bundles are embedded. It con- 

 sists of cells with comparatively thin, pitted, cellulose 

 walls, protoplasmic contents with much starch, and 

 with intercellular spaces. 



On the external surface of those parts of the cell- walls which 

 adjoin the intercellular spaces numerous small projecting spikes 

 may be observed : it may be readily seen that these originate in 

 connection with the formation of the intercellular spaces. 



Internal glandular hairs are also found in the intercellular 

 spaces ; they are attached by narrow stalks to single cells of 

 the parenchyma : the globular head contains when fresh a 

 resinous secretion, which is soluble, but not readily, in 

 alcohol. 



c. The Vascular bundles, of elliptical outline ; 



