REPRODUCTION, VEGETABLE (VEGETABLE OVUM). 



is no less important, as forming another con- 

 necting link between the Lichens and Fungi. 

 The special characteristic of these organs is 

 to be found in their containing, instead of 

 thecae or paraphyses, stylospores, supported 

 on stipitiform pedicles or basidia. In their 



Pycnidis of the same, about 150 diam. 



The stylospores are escaping from the upper ori- 

 fice of the organ. (The figures from 143 to 154 in- 

 clusive, are after Tuiasne.) 



general form they resemble the spennogoniae, 

 but their walls are thicker.and they are larger. 

 Like them they are provided with a vertical 

 ostiole. The stylospores are oblong, cylin- 

 drical bodies, more than twice the length of 

 the spermatia (from -^^ to -^^ f an inch), 

 obtuse at both ends, very slightly curved, 

 colourless, and containing only granular pro- 

 toplasma. They are supported on pedicles, 

 which have the same arrangements as in the 

 spermogoniae. They are simple, linear tubular 

 filaments, which taper towards their extre- 

 mities. Just as the spermogoniae correspond to 

 the spermatium-bearing organs of the Fungi, 

 the pycnides correspond to those receptacles, 

 containing stylospores, which we have had 

 occasion to describe both in the Discomycetes 

 and Pyrenomycetes. 



50. Summary. The reproductive organs of 

 the Fungi and Lichens are of five kinds : 

 1. Sporules, which are formed by the con- 

 striction and subsequent separation of the 

 extremity of a simple cylindrical filament ; 2. 

 Spermatia with their supporting pedicles ; 3. 

 Stylospores, with their styles ; 4. Thecae or 

 asci; o. Basidia, with their basidiospores. 



Of these the last mentioned are to be found 

 only, as we know at present, in Fungi which 

 are provided with no other reproductive organ. 

 The first four, on the other hand, all of them 

 occur in plants belonging to one family of 

 Fungi viz. the Disco- and Pjreno-mycetes : 

 they also all occur, with the exception of 

 the first, among the Lichens. They may be 

 arranged, as regards the complexity of their 

 form and structure, in the order in which they 



231 



are placed above, the simple acrogenous 

 sporule standing first. A similar arrangement 

 may also be adopted in the description of the 

 corresponding varieties in the reproductive 

 phenomena which manifest themselves in con- 

 nection with each variety of spore-like body. 

 As regards the first of these, nothing further 

 need be said, as the formation of the sporule 

 by division, as described above, constitutes 

 the whole reproductive process. It is exem- 

 plified in the stroma of a Sphoeria, when in 

 a condition corresponding to that which cha- 

 racterises a Melanconium. The spermatium 

 is found only in a special receptacle, the 

 general form and structure of which remain 

 always the same, as in the Cytispora-like 

 capsule of the Disco- and Pyreno-mycetes 

 and the spermogoniae of the Lichens. The 

 stylospores are also formed in special organs 

 (pycnides, and the corresponding organs 

 among the Fungi), which differ from the last 

 only as regards the structure of the parts 

 upon which the spore is immediately sup- 

 ported. Lastly, the receptacles which bear 

 thecae are of larger size, more complicated 

 in their structure, and later in making their 

 appearance than any of the rest, as in the 

 instance of the disc of Peziza, the closed re- 

 ceptacle of Sphceria, and the apothecium of 

 the Lichens. 



51. The Pyreno- and Disco-mycetes are, as 

 we have seen, so closely allied to the Lichens 

 as regards their reproductive organs, that the 

 characters of the two families seem in this 

 respect to merge into each other. The dis- 

 tinction is to be sought in the vegetative 

 system. The thallus of the Lichen differs 

 from the thallus-like stroma of the Fungus in 

 its possessing two additional elements, the 

 cortical layer and the gonidia. We observe 

 their first appearance in the mosc simple form 

 in Verrucaria. 



52. There is as yet no sufficient ground for 

 definitively concluding that the reproductive 

 functions of the asci and spermatia are com- 

 plementary to each other ; or, in other words, 

 that these organs are sexual. There is, how- 

 ever, good reason for considering it probable; 

 first, because, when spermatia and asci are 

 produced on the same mycelium, the former 

 always precede the latter in their develop- 

 ment by a considerable period, just as among 

 the higher Cryptogamia, the antheridia precede 

 the archegonia ; and, secondly, because the 

 organs on which the spermatia are supported, 

 and the asci, stand in an anatomical relation 

 to each other, and to the receptacle within 

 or upon which they are formed, which closely 

 resembles those of the antheridia and epispores 

 of the Fuci, or of the antheridia and tetraspores 

 of the Florideae. We are well aware that 

 these analogies do not afford the slightest 

 proof of an actual correspondence between 

 the organs in question. All more direct 

 evidence, however, is absent ; no observations 

 have been made to show that the spermatia or 

 stylospores exercise any influence on the thecae 

 or their contents, and on these important 

 points, therefore, we must look to further ob- 



Q4 



