76 REVUE BKYOLOGI0L"E 



V 



and swell up greatly on the addilion of water. From the walls 

 of each antheridial cavity there grow in numerous club-shaped 

 unicellular hairs, which are also mucilaginous. 



The development of the ANTiiEiuniUM of Monocka entirely 

 agrees with what is observed iu the Marchantiacea. A cell 

 projects from the surface and hecomes divided by three or four 

 transverse walls, so that the young antheridium consists of a 

 short row of cells, previous to the appearance of the first vertical 

 walls (Fig. 3, B.). The latter intersect so as to divide each cell 

 into four, but they are not formed in this regular manner in the 

 upper and the lower cells of the antheridium, which remain for 

 some time undivided and then divide irregularly. The mature 

 antheridium is ovoid, having a short stalk and tapering above 

 to a pointed beak. Aftei; the anthcridia have discharged their 

 contents, the large-celled mucilaginous tissue becomes dried up 

 and disintegrated, so that an old receptable shows a large space 

 open in front and roofed over by, the upper zone of small-celled 

 green tissue. In this condition, the male receptacle strongly 

 resembles, at first sight, one of the female receptacles, and its 

 real nature is only made out when sections are examined. 



The writer has recently observed in several cases well-marked 

 explosive discharges of the antherozoids in MonocUa. On placing 

 a drop of water on the surface of a male receptacle, jets of spray 

 were seen to issue from the openings of the antheridial cavities. 

 These jets, which sometimes reached a height of G to 8 cm., 

 contained large numbers of antherozoids. On examining sections 

 of a receptacle after several of these jets had issued from it, the 

 antheridial cavities are found to be almost obliterated, each 

 chamber containing an empty and greatly compressed antheri- 

 dium. The main cause in producing the discharges is obviously 

 the pressure set up when the large-celled mucilaginous tissue 

 absorbs water and becomes swollen. 



The ARCHEGONiAL RECEi'TAcxE is developed at the end of a 



branrh (Fig. 1, B.), and, owing to the vigorous growth of the 

 surrounding tissue, becomes sunk in a depression which is pro- 

 duced forwards into a long, narrow canal opening at the ante- 

 rior margin of Uie Ihallus (Fig. 3, C). Between Ihe archegonia 

 there arise numerous mucilage-lmirs, and the cavity usually con- 

 tains a large quantity of mucilage. The archegonium has a very 

 long neck (about 07 mm.) and a short, thick stalk. The neck 

 cells are arranged in six rows (Fig. 3 D.), which were invariably 

 nearly or quite straight in the material examined by the writer, 



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