146 THE PLANT CELL. 



is thus homologous with the prothallus of Homosporous Pteri- 

 dophyta; but, as has just been seen, both gametophyte and 

 sporophyte are united in the same plant. The musci are also 

 propagated by a vegetative method — viz., by means of gemmsB, 

 which are small cellular offshoots of the gametophyte. 



2. Keproduction in Hepaticse (Bryophyta). — Here there is 

 also an alternation of generations, and the reproductive organs, 

 antheridia and oogonia, are found on the gametophyte, or sexual 

 generation (which has often the form of a simple flattened 

 structure), upon the under surfaces of special fructifications. At 

 times a type of vegetative propagation occurs, in that gemmae, 

 or buds, composed of a few cells, are formed, usually at the 

 bottom of small cup-shaped receptacles (Marchantia). The result 

 of the fusion of an antherozooid with the oosphera in an 

 oogonium is the oospore, which divides and forms a sporogonium, 

 which is the sporophyte, or asexual generation. In the sporo- 

 gonium the spores are produced, and germination of a spore 

 results in the production of the thallus, gametophyte, or sexual 

 generation once more. In Riccia, the sporogonium is quite a 

 simple structure, whilst in Anthoceros it forms a more complicated 

 growth. * 



3. Reproduction in the Fungi (Thallophyta). — Two main 

 methods of reproduction occur, viz., an asexual, by means of 

 spores, and a sexual type {Phycomycetes), often of the nature 

 of conjugation. In the former, or asexual method, spores are 

 often formed at the ends of special hyphal branches or 

 gonidiophores, the spores being here known as gonidia (Mucor). 

 At times, on the other hand, the ends of certain hyphae develop 

 into special strutures known as asci, which are enclosed in an 

 ascocarp, and spores (ascospores), to the number of eight, are 

 formed in these in rows, being, later on, freed by rupture of the 

 asci. Spores may also be formed in sporangia (endospores). 



In the more highly differentiated Fungi (Agaricus, &c.), large 

 fructifications are formed, and on the under surfaces of the ter- 

 minal parts of these — viz., the hymenium — delicate lamellaB are 

 produced, from the two surfaces of which spores arise upon 

 hyphal structures known as basidia, there being four spores to 



* The sporogonium at times develops a "foot," wtiich attaches it to 

 the gametophyte. In Anthoceros (Hepaticce) and Funaria {Mu.ici) the 

 foot is well marked. 



