226 MORPHOLOGY OF MEMBERS. 



but this leafy plant docs not, as in the case of the F(^rn, produce spores, but can be 

 reproduced by bulbils of different kinds. At length however, like the prothallium 

 of Ferns, it produces sexual organs, and an embryo is the result of the fertilisation 

 of the oosphere : this is not connected organically with the Moss-plant, but remains 

 attached to it, deriving its nourishment from it, and finally developes into a capsule 

 supported on a long stalk, the Sporogomu?n, in the interior of which are produced 

 numbers of spores. A number of these stalked capsules, i. e. entire generations, 

 may arise on the same Moss-plant either simultaneously or successively. The 

 course of development of a Moss is therefore divided into two sharply separated 

 stages, VIZ. the formation of a leafy stem which produces sexual organs (oophore), 

 and the production of stalked capsules out of the fertilised oospheres of the female 

 organs. In Muscinese the second or asexual generation (sporophore), the sporo- 

 gonium, has no power of directly producing its like from itself, as is possible in 

 the case of Ferns, by bulbils; its only function is to produce spores^; and when 

 the spore germinates it gives rise first of all to a Protonema, which sometimes con- 

 tinues to grow for a long while, and can reproduce itself by gemmse, until at lengh 

 Mo 3s- stems with true leaves again appear on it, which also are capable of multi- 

 plication by means of bulbils. 



Even in Thallophytes we meet with various forms of an alternation of gene- 

 rations^. It is well shown in certain Fungi of the class Ascomycetes which have 

 been closely investigated, as, for example, in the common mould, Penicilliwn 

 glaucum, the ordinary form of which is only the first generation or stage of 

 development in its life. During this stage, the first or sexual generation, the 

 so-called Mycelium, developes on special branches a number of cells {conidia), 

 by which the Fungus is continually propagated in this form. But when the 

 excessive development of these conidia is prevented by exclusion of the air, 

 sexual organs arise, as Brefeld has shown, on the luxuriant mycelium, and in 

 consequence of their union a tuberous body is formed of a totally different 

 nature, within which spores are finally produced in extremely numerous sacs 

 {asci) of peculiar form; and these, when they germinate, again produce the 

 mycelium with its penicillate conidiophores. The mycelium of this Fungus 

 (and strictly speaking of all Fungi) corresponds therefore to the first stage of 

 development, the prothallium, of Ferns, or to the leafy Moss-plant; and all three may 

 be considered as the Sexual Generation [oophore], since their normal development 

 ends with the formation of sexual organs. In all three cases, this sexual gene- 

 ration (prothallium, Moss-plant, mycelium) may propagate itself by gemmae or by 

 conidia before it produces the sexual organs. The small tubers which are the result 

 of fertilisation in Penicillium correspond to the second stage of development, viz. 

 the sporogonium of Mosses, and the mature Fern-plant^; in all three cases the 

 product of this second generation [sporophore] is a large number of spores, by 



^ [The researches of Pringsheim and Stahl however have shown that this linaitation can no 



longer be maintained. See Book II. Group 2.] 



^ [This explanation is now no longer generally accepted ; see Journ. of Botany, 1879.] 



^ If these small tubers in Penicillium are termed the fructification, then in the same 



sense the sporogonium of Mosses is a fructification; and the Fern is also the fructification of 



the prothallium. 



