C2 FERTILIZATION AND FEUIT-FORMATION IN CRYPTOGAMS. 



mother-plant, but differs conspicuously in form from the generation from which it 

 sprang. This stage having already been dealt with on p. 22, it is here only 

 necessary to mention briefly that the cells of the fruit begin to shoot out after a 

 period of rest of variable duration and abstrict a mass of spores, and that in 

 addition, in most Floridese, linear series of cells grow from the cells at the base of 

 the fruit, and form a capsular envelope around the young spores. 



The Cryptogams that we have still to deal with, viz. : the Characere, Muscinese, 

 and Vascular Cryptogams, differ from those already described in that the oogonium 

 is wrapped up in a special sheath before fertilization takes place, and that the 

 entrance-passage provided for the spermatoplasm is consequently modified in a 

 characteristic manner. This sheath, to which we shall apply the term amphi- 

 gonium (also known as archegoniuTn), is in the main of the same construction in 

 all the plants exhibiting it; but as regards the penetration of the spermatozoids 

 into the amphigonium, and the behaviour of the fruit produced from the fruit- 

 rudiment, there are very considerable differences amongst the groups in question. 

 To follow out these diversities in minute detail is not possible within the narrow 

 limits of this book, and I must content myself in the following pages with giving 

 a brief sketch of the most important phenomena. 



To begin with the Stoneworts (Characese), we find that in them the fruit- 

 rudiment is ellipsoidal in shape, and is borne on a very short unicellular stalk. 

 This stalk is seated upon the so-called "nodal cell", a short discoid cell which 

 forms the pedestal of the large ellipsoidal oogonium, and also gives rise to five 

 tubular cells arranged in a whorl, and twisted spirally round the oogonium, thus 

 enveloping it in a sheath of great beauty (see fig. 206 ^). From the ends of these 

 investing tubes, which project above the oogonium, small cells are separated off, and 

 together constitute a little roof for crown to the amphigonium. Beneath the crown 

 the enveloping tubes are drawn together so as to form a neck which incloses a 

 narrow cavity, and this is the part where at the time of fertilization fissures are 

 formed between the otherwise connate tubes of the envelope, thus enabling the 

 spermatozoids to penetrate into the interior of the amphigonium, and to reach the 

 ellipsoidal oogonium there matured. 



The mode of genesis of these spermatozoids is extremely remarkable. They 

 are produced in certain red, globular structures, which are slightly smaller than 

 the fruit-rudiments and have a like origin — that is to say, they take their rise 

 amongst the whorls of lateral offshoots. In some species they are formed on the 

 same individuals as the fruit-rudiments (c/. figs. 206 ^ and 206 '), in others the two 

 kinds of structure develop on different individuals, and are thus separated from one 

 another; hence we distinguish Charace^ into monoecious and dioecious species. 

 Each red sphere is composed of eight plates, outwardly slightly convex. Each of 

 these is in the shape of a spherical triangle with indented edges and folds running 

 radially from the centre to the notched margins (see fig. 206*)- The plates 

 are joined together into a sphere, the notches of the margins fitting into one 

 another so as to form a regular dovetailed suture. From the centre of the gently 



