PLATE XX— MOONWORT (Lunularia vulgaris) and VARIABLE LIVERWORT (Marchantia polymorpha). 



Lunularia. 



Lunularia, so named from its crescent-shaped receptacles, is found on neglected flower-pots left in a dam]) and shady place, and such 

 like. It only produces buds in this country and is very convenient for seeing the Gemmae at different stages, while the Marchantia 

 may serve for tracing the sexual process. It forms a small, bright-green bifurcating Thallus. 



Fig. la. Female plant with fertile branch, forming a cross-shaped apex bearing Archegonia 



Fig. lb and c. The gemmae-bearing plant, with a forked growing apex, and withering away behind. The upper surface has 

 gemmae-cups and the under surface a tangled line of root-hairs. 



Fig. 2. Upper surface of Thallus under simple microscope shows irregularly shaped tracts with Respiratory-pore in centre of 

 each. 



Fig. 3. Peel off a very thin slice of epidermis and examine under high power. 

 Opening of Respiratory-pore (seen in section, in Fig. 7). 



Fig. 4. Embed small portion of Thallus in paraffin and make tranverse section. 

 Upper Epidermis of close-fitting cells. 

 Respiratory-cavity containing green cell". 

 Colourless cells. 



Lower Epidermis, giving rise to Root-hairs, each composed of a single cell and with walls, strengthened by 

 incomplete spiral thickenings. 



Fig. 5. Embed a young Receptacle in paraffin and make transverse section. 



The Gemmae are seen at all stages of development, from little pear-shaped bodies (1) till they reach maturity (8), 

 ready to be detached and shed. 



Marchantia. 



Marchantia is very common in moist or damp places, spreading over damp rocks or soil, or on the mould of flower-pots. It is a 

 leathery flat expansion and grows by repeated bifurcation at one end, so that it gradually forms a fan-shaped mass. The upper surface 

 is dark-green, while the under surface, in contact with the soil or rock, is pale in colour. There are not only root-hairs on the under 

 surface to fasten it, but a double row of membranous appendages which are apparently comparable to leaves. 



Fig. 6a. Male plant with fertile branch spread out at the top in umbrella fashion. The upper surface of this fertile branch 

 is studded with little openings which are the mouths of sacs containing Antheridia 



Fig. 6b. Female plant with fertile branch expanded at the top into a star-like disc bearing Archegonia on its under surface. 

 The cup-shaped receptacle with toothed margin contains gemmae. 



Fig. 7. Embed piece of cup in paraffin and make section — or a piece of the Thallus may be used. 



On the inner surface of cup (lower surface in drawing) the cells are relatively large and colourless, and the 

 outer surface has its epidermal cells close together. Beneath the epidermis there are Respiratory cavities containing 

 branched rows of chlorophyll-containing cells, to which air has admission through the little openings seen on the 

 surface of the Thallus (Fig. 2) called Respiratory-pores. 



The object of this arrangement is only to admit the air where most wanted. The general arrangement of the 

 tissues is impermeable to air, and the plant does not readily dry up, from its tough and leathery texture ; but by 

 means of these little lung-like chambers the air plays freely among the spread-out green cells and enables them 

 to decompose carbonic acid in the presence of sunlight. 



Fig. 8. Embed portion of male plant containing Antheridia and make sections. Examine first under low power, then add a 

 drop of spirit, afterwards glycerine, and examine under high power. 



Antheridium with stalk, an outer wall, and inner mass of cells developing antherozoids. 



The ripe antheridium bursts irregularly on one side to discharge its contents. The cell-walls swell up with 

 water and burst, then the gelatinous contents poured out are gradually dissolved by the water, and the freed anthero- 

 zoids may be seen moving about with two cilia. 



Fig. 9. Ripe Archegonium, showing the margins of the lobes of the disc growing down to form a sort of investment or 

 perianth. 



Fig, 10. Sporogonia or Spore-fruits on under surface of disc, consisting of rounded bodies. 



The interior mass of cellular tissue is converted into alternating rows of spores and spiral filaments. As water 

 is absorbed the spore-capsule bursts and, under the same influence, the spiral filaments, coiled up like a spring, 

 spread out and scatter the accompanying spores with considerable force. 



Fig. 11. Spores and Elaters. 



The Elaters are doubly coiled filaments enclosed by a wall. 



Life History of Marchantia. — Marchantia multiplies by asexual buds or Gemmae, which are little green bodies enclosed in cup- 

 shaped receptacles, and on becoming detached, may develop into new individuals. 



Marchantia also reproduces itself sexually. The male organs (or Antheridia) and the female organs (or Archegonia) are 

 borne by different individuals. The Antherozoids fertilise the central cell of the Archegonium, converting it into an Oospore 

 which swells up and grows into a Sporogonium full of spores. The spore germinates, producing the green, flat expansion, 

 as at the beginning. 



