^r.' 



14 



YORKSHIRE NATURALISTS UNION. 



The branches are in fascicles or bundles of four to twelve in 

 each, part of them spreading outward, and part of them pendent 

 and closely applied to the stem. The leaves arc always nerveless, 

 and consist of two very different kinds of cells, first, large empty 

 vesicular cells, having the walls perforated with circular lioles, 

 and on the internal wall fine fibrils wound round in spirals or 

 rings, just like the hoops in a lady's crinoline, to keep it 

 expanded ; secondly, slender tubular cells filled with chlorophyl 

 placed between and around the large vesicular cells, and the 

 relation of these cells to each other is of great importance in 

 the discrimination of species ; this is seen by transverse section 

 of the leaf, when the chlorophyl cells appear between the 

 vesicular, either lenticular, if placed centrally", or bluntly 

 triangular with the base projecting either at the dorsal or ventral 

 surface. The male inflorescence is packed on the upper 

 branches which thus become clavate and colored, the anthcridia 

 being globose, stalked, and standing singly by the side of each 

 bract. 



The archegonia resemble those of mosses, and the capsule 

 is enclosed in a large saccate calyptra, and afterwards elevated 

 naked brancli; in shape it is globose, with a flat lid and no 

 trace of peristome. The great uniformity in habit renders it 

 difficult to define species, and there is a tendency at present to 

 largely multiply them, though all of them vary exceedingly. 



The Hepaticcc differ still more widely from mosses, although 



e species are often mistaken for them, and their simpler 



structure shows that they are of lower organization. Besides 



the leafy species a number remain in the thalloid state, that is. 



on a 



som 



/ 



> 



J 



^ 



\ 



Pot, Trans. Y.N.U., 1891 (pub. 1S9()). 



