FERTILIZATION AND FRUIT-FOEMATION IN CRYPTOGAMS. 61 



filamentous cell called the trichogyue (fig. 204 ''). Rudimentary fruits of this kind 

 are produced on one individual, whilst antheridia are formed upon another. It is 

 much less common for fruit-rudiments and antheridia to be developed on the same 

 individual, and in the few species which do exhibit this combination, self-fertilization 

 is rendered practically impossible by a retardation of the development either of the 

 fruit-rudiments or of the antheridia. The antheridium always takes the form of a 

 limited portion of the thallus, from which separate round cells filled with spermato- 

 plasm are thrown off. Fig. 204^ represents an antheridial branch of Dudresnaya 

 coccinea. A slender branch of the thallus terminates in a group of cells arranged 

 dichotomously, and the outermost of these cells, which become rounded off" and 

 detached, contain the spermatoplasm, and must be looked upon as spermatozoids. 

 Unlike the spermatozoids of Vaucheria and those of the Characese (Stoneworts), 

 Muscinese, and Ferns, to be described presently, these have no cilia, and do not 

 move by virtue of any power of their own in the surrounding water, but are 

 carried about by currents which are always more or less prevalent at the places 

 where the Florid ese live. Through the action of these currents in the sea, the 

 spermatozoids (or spermatia as they are called) reach one of the trichogynes 

 and adhere to it, as is shown in fig. 204 ^. The question as to how far attractive 

 forces emanating from the ooplasm come into play in order to effect this conjunc- 

 tion must remain undecided. It is not impossible that substances may be secreted 

 by the ooplasm and be given off" into the environing water, and that they may 

 take part in the phenomenon. Nothing more definite is known beyond the evident 

 fact that the spermatozoids adhere much more commonly to trichogynes than to 

 other objects floating in the neighbourhood. Part of the protoplasm of the adherent 

 cells passes apparently by osmosis into the protoplasm of the trichogyne. The 

 change ensuing upon this process is transmitted to the protoplasm occupying the 

 ventral enlargement at the base of the trichogyne, and in many cases even further 

 to the protoplasm of adjacent cells. Although this propagation of the change in 

 the molecular structure of the protoplasm cannot be directly observed, it may be 

 assumed on various grounds, and we may fairly suppose that the action of the 

 absorbed constituents of the spermatoplasm upon the ooplasm is comparable to that 

 of certain enzymes, which have a convulsive effect upon any protoplasm in their 

 vicinity, and even when they are separated from it by cell-walls cause a displace- 

 ment and rearrangement of the molecules (see vol. i. p. 464). That the change 

 affecting the protoplasm at a particular spot in the fruit-rudiment is capable of being 

 propagated so long as any protoplasm susceptible of the same change is present, is 

 proved by the fact that it is not the trichogyne itself but the ventral enlargement 

 at its base and the cells adjacent to this enlarged portion which undergo subsequent 

 development. They increase in bulk, whereas the trichogyne shrivels and dies. 

 The cells which contain the protoplasm fertilized through the intervention of the 

 trichogyne must, in my opinion, be looked upon as the fruit. Any subsequent 

 structure arising from them is no longer fruit but a new generation. In Florideas, 

 as in so many other cases, this new generation preserves its connection with the 



