22 SPORES AND THALLIDIA. 



Nothing then remains but the hyphal filament with its swollen end beset with pegs 

 and looking like a club armed with spikes (c/. fig. 193 *). 



Also in PeniciUium, the commonest of all Moulds, the spores are abjomted 

 from the sterigmata in moniliform rows; but in this case the erect hypha which 

 bears the spores is septate and not clavate at the extremity, and terminates in 

 forked branches, so that the chains of spores are grouped like the hairs in a camel's- 

 hair pencil. A species of Penicillnim— viz. P. crustaceum— is represented in 

 fig. 193^ and 1938). j^ the Peronosporese, to which class belongs the parasite 

 Cystopus candidus, celebrated for its fatal effects on cruciferous plants, moniliform 

 rows of spores are abjointed from the basidia without the intervention of sterig- 

 mata. The mode of arrangement of the chains of spores in this parasite is, how- 

 ever, not quite like that in either PeniciUium or Aspergillus. 



A further diversity in this kind of spore-formation by process of abj unction 

 is introduced by the presence in several families of plants of special envelopes 

 surrounding the abjointed spores. Particular cases of this are afforded by 

 Gasteromycetes (Puff-ball family) and Floridese (Eed Seaweeds) and by that stage 

 in the development of the Rust-Fungus which is known by the name of ^cidium. 

 The secidia make their appearance in the form of structures growing out from 

 a mycelium infesting the green tissues of leaves. The basidia are formed by the 

 ends of hyphse which stand up in dense crowds. Moniliform chains of spores 

 are abjointed from the basidia and are enveloped by a sporangium-like wall 

 developed from the cells surrounding the basidia. It is not till this enveloping 

 capsule bursts that the spores are set free and can be distributed. 



In the large Puff-Bail family (Gasteromycetes) the same process takes place, 

 but the basidia and spores are not arranged so regularly, and amongst the spores 

 are to be found other hair-like, cellular structures which constitute what is termed 

 a capillitiwm and are of especial importance in relation to the distribution of the 

 spores. Floridese develop their spores within receptacles peculiar to themselves, 

 which frequently resemble urns or capsules, and might be designated sporangia 

 for the sake of terminological uniformity. The spore-filled "sporangia" of Floridese, 

 like those of Muscinese — and in particular of Liverworts — are to be conceived as 

 a separate generation, and, moreover, as a generation springing from cells which 

 have undergone fertilization and have thereby been converted into fruit. The 

 description of the process of fertilization must be postponed to a later section 

 of this book; we have only to notice here that short cells are put forth as branches 

 from the fertilized cells, and that some of these branches abjoint clusters of spores 

 whilst the others develop into a sheath enveloping the assemblage of spores thus 

 produced. 



Under the name of Thallophytes are included all such plants as are destitute of 

 vascular bundles and therefore are never developed into real plant-bodies (cf. vol. i. 

 pp. 590-592). It often happens that Thallophytes form, in addition to the uni- 

 cellular brood-bodies to which the name of spore must be limited, cell-aggregates 

 which sever themselves from the thallus and become independent, the genesis of 



