CHAP. III. HEPATICiE. 227 



differences in the number or cohesion of which the generic 

 characters of mosses are in a great measure formed. For 

 further information upon the peristomium I must refer to 

 Brown's remarks upon Lyellia, in the 12th volume of the 

 Linnean Transactions. 



Tlie interior of the theca is commonly unilocular ; but in 

 some species, especially of Polytrichum, it is separated into 

 several cells by dissepiments originating with the columella. 



If at the base of the theca there is a dilatation or swelling 

 on one side, this is called a struma ; if it is regularly lengthened 

 downwards, as in most of the Splachnums, such an elongation 

 is called an apophysis. 



In Andrteaceae the theca is not an urn-like case, but splits 

 into four valves, cohering by the operculum and base. 



From the foregoing description, it will be apparent that the 

 organs of reproduction of mosses cannot be said to be analo- 

 gous to the parts of fertilisation of perfect plants. I must 

 not, however, omit the opinion of other botanists upon this 

 subject. The office of males has been supposed by Micheli 

 to be performed by the paraphyses ; by Linnaeus and Dille- 

 nius, by the thecae ; by Palisot de Beauvois, by the sporules ; 

 by Hill, by the peristomium ; by Koelreuter, by the calyptra ; 

 by Gaertner, by the operculum; and, finally, Hedwig has 

 supposed the males to be the staminidia. The female org-ans 

 were thought by Dillenius and Linnaeus to be assemblages of 

 staminidia ; by Micheli and Hedwig, the young thecee ; and, 

 by Palisot de Beauvois, the columella. 



For some suggestions as to the analogy that is borne 

 between the organs of mosses and of other plants, see Mor- 

 phology hereafter. 



6. Jungermanniacece and HepaticcB. 



These differ remarkably from each other in die modi- 

 fications of their organs of reproduction, while they have a 

 striking resemblance in their vegetation. This latter, which 

 bears the name o^ frond or thallus, is either a leafy branched 

 tuft, as in mosses, A\dth the cellular tissue particularly large, 

 and the leaves frequently furnished with lobes, and appendages 



Q 2 



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