326 



HEPATIC^ 



The stomata vary a good deal in size and structure, in the 

 more cellular frondose species they are but little elevated, and 

 are nothing but a space existing between a certain number of 

 the cells of the cutis, but in the more perfect types, as Mar- 

 chantia, they terminate rounded elevations above the surface, 

 and all the cells entering into their formation which have no 

 green matter adhering to them, are distinctly radiate and plu- 

 riseriate. 



The appearances presented by a transverse section of the 

 frond, are deceptive so far as regards the roots, for they then 

 appear to occupy chiefly two spaces on either side of the 

 mesian line, each space being cut off on either side by scales, 

 but they are in reality developed indiscreminately from the 

 under surface (except from that which may be called the intro- 

 marginal space,) and they are deficient here, probably because 

 this is not in contact with the soil ? They do not form any 

 continuous line, except perhaps exactly along the centre, but 

 form oblique lines in the same direction as the scales, con- 

 verging towards the central part of the frond. 



The exact nature of this cuticle, can only be determined 

 by examining the young fronds. 



There is no distinguishing essential mark between nos. 25, 

 26, and 27, (p. 297), except that derived from the point of 

 departure of peduncle from the frond ; of the value of this 

 I am not aware. The capsular dehiscence is in all probably 

 circumcision. No. 25 has no stomata on its caput, but I 

 am not aware what value is to be attached to this, or to the 

 stalk of its capsule, it may be, that the subgenus No. 27, is 

 the most developed, and borders closely on Marchantia, to 

 which in its peduncle it approaches, except in its being es- 

 tomatose, and only having one groove. 



It is evident from these three species, that the perfection 

 of the frond is in direct ratio with the complication of the 

 peduncule, (of course) ; and in No. 25, in which it is not ter- 

 minal, the frond is laxly cellular, equally in proportion is the 

 stomatosity of the caput. 



