MARCHANTIA. OOPHORE. 21 



by the form of the cups containing the gemmae, these being, as 

 the name Lunularia implies, of a semilunar form. It is to be 

 remarked further that Lunularia differs from Marchantia in 

 certain structural details ; and also in the fact that, though 

 reproduction by gemmae is most profuse, a sexual reproduction is 

 not effected in this country. Thus it cannot be taken as a substi-" 

 tute for Marchantia, and the material must be carefully sorted 

 before use. 



For comparison with Marchantia, observations should also be 

 made of other allied forms, e.g. Riccia fluitans, which is of 

 simpler structure, and of much smaller size ; it branches dichoto- 

 mously, and the branches in this case often develop equally. If 

 a fresh thallus of Riccia be examined under a low power, it will 

 be seen to consist of green chlorophyll- containing cells, with 

 numerous large intercellular spaces, and the apex will be seen 

 to be depressed ; on the under surface will be found small 

 amphigastria. 



A comparison should also be made with Pellia, in which the 

 thallus is of a broad, frondose form, of simple structure. 



Some species of Jungermannia should also be examined : here 

 the shoot will be found to be dorsiventral, but of more complex 

 external form than that of Marchantia in addition to the amphi- 

 gastria, there are also present lateral appendages or " leaves," which 

 are thin, flattened expansions of green chlorophyll- containing 

 tissue, inserted on the relatively thin axis. 



B. MICROSCOPIC OBSERVATIONS. 



III. Cut transverse sections of the vegetative thallus 

 of Marchantia, avoiding at first the cups bearing the 

 gemmse, and the sexual branches. It is easier to use 

 material hardened in alcohol, and to embed it in 

 paraffin, or hold it between pieces of pith; but if 

 sections be cut from fresh green material the presence 

 of chlorophyll will be found to be an advantage in 

 distinguishing the tissues. Mount some sections in 



