285 



HEPATICJ1. 



General Remarks. 



In making the following observations it is not my intention 

 to enter into details of the anatomy of the plants of the or- 

 der Hepaticse, particularly as that of the cuticulate species 

 has already received abundant notice in the celebrated me- 

 moir of M. Mirbel on Marchantia 



The usual from of the order is frondose, although the num- 

 ber of foliaceous species of Jungermannia, probably far exceeds 

 that of the species of all the remaining genera. 



The frondose species are chiefly remarkable for their great 

 tendency to a binary division. They maybe conveniently di- 

 vided into. 



Cuticulate, and Ecuticulate. 



If the former j the upper cutis is supplied with large open 

 orifices ; the existence of which, although it had been al- 

 luded to, does not appear to have attracted much attention 

 before the publication of M. Mirbels memoir. Their organis- 

 ation is in all the species the same ; and they may be consider- 

 ed as characteristic, their existence out of the order, having only 

 I believe, been ascertained in Kaulfusia 



The under cutis presents nothing remarkable except its ten- 

 dency to assume a more or less purple colour. 



The radicles are excessively numerous, and are, at least in 

 the frondose species, always simple. They are in fact nothing 

 but an elongation of some of the cells forming the lower stra- 

 tum of the uncoloured parenchyma. In the ecuticulate species, 

 they pass to their destination without interruption, but in the 

 cuticulate, the inferior cutis is obviously interposed. It is 

 owing to this origin of the radicles, and to the force which they 

 exert in passing towards the veins, that the universal presence, 

 and the direction of the scales on the under surface of 

 the fronds of these species, is to be attributed. These ra- 



