MARCHANTIA. 



Fig. 451. 



[ 413 ] 



MARCHANTIA. 



Marchantia polymorpha. 



Section through the antheridial receptacles, showing the 

 flask-shaped cavities containing the antheridia. 



Magnified 25 diameters. 



lower surface of the receptacle is clothed by 

 membranous processes and hairs. 



The female receptacles are somewhat con- 

 vex above, and on the under surface of the 

 base of each lobe are found delicate mem- 

 branous processes with toothed margins. 

 The membranes of each two adjoining lobes 

 form a perichate (fig. 452) alternating with 



Fig. 452. 



Marchantia polymorpha. 



A sporangia! receptacle seen from below. 



Magnified 5 diameters. 



the lobes, concealing between them the ar- 

 chegones, which are attached by their bases, 

 and have their mouths pointing downwards. 

 The archegones of Marchantia are flask- 

 shaped sacs with a long neck (figs. 329-331, 

 p. 320), containing in their cavity a cell (germ- 

 cell), which after fertilization becomes deve- 

 loped into an oval cellular body, the young 

 sporange. In the course of the development 

 of this, it soon fills the cavity of the arche- 

 gone, which then begins to grow with it, 

 and subsequently forms a loose sac around 



it, the epigone, finally ruptured at the point, 

 so as to exhibit four or five teeth or valves, 

 which become recurved (fig. 453). Mean- 

 Fig. 453. 



Marchantia polymorpha. 



Vertical section of the same, showing sporanges in situ, 



bursting to discharge the spores and elaters. 



Magnified 10 diameters. 



while another envelope grows up around the 

 epigone, appearing at first as a mere ring 

 surrounding it (figs. 329-331, p. 320), but 

 ultimately rising up so as to enclose it, re- 

 maining open however at the summit ; this 

 is the perigone. In its young stages the 

 sporange is a mere oval mass of polygonal 

 cells, but soon may be detected a distinction 

 between a cortical or peripheral layer and 

 the internal mass. The cells of the former 

 remain firmly united into a membrane form- 

 ing the wall of the sporange. These cells 

 grow so as to assume an elongated form, 

 and when mature exhibit internally a spiral- 

 fibrous secondary deposit (PI. 32. fig. 35), 

 analogous to that of the cells of the anthers 

 of Flowering plants. The cells of the inter- 

 nal mass present at an early period the ap- 

 pearance of a large number of filaments 

 radiating from the centre of the sporange to 

 the wall. These soon become free from each 

 other, and it may then be perceived that 

 some are of very slender diameter, and others 

 three or four times as thick. The slender 

 ones are developed at once into the long 

 elaters (PI. 32. fig. 36) characteristic of this 

 genus, containing a double spiral fibre, the 

 two fibres, however, coalescing into one at 

 the ends (fig. 37). The thicker filaments 

 become subdivided by cross partitions, and 

 break up into squarish free cells, which are 

 the parent-cells of the spores, four of which 

 are produced in each (P1.38.figs.lO-13). The 

 sporesof M^o/ymorp^ahavebuta single coat, 

 and their contents are bright yellow when 

 mature. When they germinate, the contents 

 are converted into chlorophyll, and the growth 

 commences by the production of a tubular 

 process from one side of the spore. 



