Ill  MARCHANTIE^ 57 



The highest type is that of Leitgeb's ^ " Compositae." Here 

 the female receptacle is a branch system similar to that of the 

 male receptacle of Mardiantia. The branching is usually 

 completed at a very early period, while the receptacle is almost 

 concealed in the furrow in the front of the thallus. A simple 

 case of this kind is seen in Fimbriaria Californica (Fig. 19). 

 Here there are four growing points that have arisen from the 

 repeated dichotomy of the primary growing point of the branch, 

 and each of these gives rise to archegonia in acropetal succession, 

 much as in Targionia^ but the number of archegonia is small, 

 not more than two or three being as a rule formed from each 

 apex. The development of the dorsal tissue is excessive and 

 the ventral growth reduced to almost nothing, and the growing 

 apices are forced under and upward and lie close to the stalk, 

 and the archegonia have the appearance of being formed on the 

 ventral side of the shoot, although morphologically they are 

 dorsal structures. In the common 3{farchantia polyniorpha the 

 branched character of the receptacle is emphasised by the 

 development of the " middle lobe " between the branches. 

 These lobes grow out into long cylindrical appendages between 

 the groups of archegonia, and give the receptacle a stellate 

 form. Usually in M. polynwrpha there are eight growing 

 points in the receptacle, and of course as many groups of 

 archegonia, which are much more numerous than in any other 

 genus, amounting to a hundred or more in one receptacle. In 

 Marchantia^ as well as some other genera with compound 

 receptacles, there are two channels in the stalk, showing that 

 this is here influenced by the first dichotomy. While the 

 archegonia, before fertilisation, are quite free, the whole group 

 of archegonia, and indeed the whole receptacle, is invested with 

 hairs or scales of various forms that originate either from the 

 epidermis of the dorsal side, or as modifications of the ventral 

 scales. 



The lacunar tissue is very much developed upon the 

 receptacles, as are to an especial degree the peculiar cylindrical 

 breathing pores. The formation of these begins in the same 

 way as the simple ones, being merely the original opening to 

 the air-space. This seen from the surface shows an opening 

 with usually five or six cells surrounding it. Vertical sections 

 show that very soon the cells surrounding the pore become 



1 Leitgeb (7), vol. vi. p. 33. 



