HARDWICKE'S SCIENCE-GOSSIP. 



85 



minute, colourless, simple cells called conidia, which 

 are easily detached and float in the water in which 

 the section is immersed. A section of one of the 

 brown and wrinkled tubercles shows quite a different 

 structure : there is a common stem or receptacle, called 

 a stroma, containing several hollow sacs, or perithecia, 

 each communicating with the exterior by a narrow 

 neck, and containing the sporidia, which are deve- 

 loped in narrow, elongated, transparent sacs, the 

 asci ; each ascus contains eight semi-setate sporidia. 

 In this example the two stages classed according to 

 the fruit would belong respectively to the two primary 

 divisions of fungi ; the first or conidia stage, produc- 

 ing naked fruit, would belong to the sporifera ; the 

 second, or ascophore, to the sporidifera, characterised 

 by having the sporidia contained in asci. It may be 

 well to explain that the term "spore" is restricted to 

 those germ-cells which are not contained in sacs or asci, 

 " sporidia " to those which originate from the break- 

 ing up of the contents of asci in which they remain 

 enclosed until mature. The sporidifera contain two 

 families, Ascomycetes, characterised by the saCs spring- 

 ing from a basal collection of cells — the hymenium — 

 and each ascus containing a definite number of 

 sporidia, generally eight, illustrated by the genus 

 Nectria. Another genus, Sphcvria, including nearly 

 two hundred British species, also belongs to this 

 division ; they are all minute and appear under the 

 form of black rounded bodies terminating in a more 

 or less elongated papilla, or neck, through which 

 the sporidia escape. The globular receptacle, or 

 perithecium, containing the asci, is frequently quite 

 immersed in the branch or leaf on which the plant 

 grows, the projecting neck affording the only evi- 

 dence of the presence of the parasite. This genus is 

 separated from Nectria by the absence of a stroma ; 

 the latter, therefore, may be considered as a com- 

 pound Sphoeria. The accompanying figures will render 

 evident the relationship and differences between the 

 two genera. S. acuta, common on dead-nettle stems, 

 has a smooth, conical perithecium with a short 

 thick neck, or ostiolum, sporidia fusiform, with many 

 septa or divisions in the endochrome, slightly curved 

 and arranged more or less in two rows in the ascus. 

 A plant differing in [structure is equally common in 

 the same situation, the perithecia rounded, ostiolum 

 long and cylindrical ; a section will reveal, in place 

 of numerous asci, a mass of very minute free cells, or 

 spermatia. This is not now considered as a distinct 

 species but a form of the preceding, JT. acuta, and 

 is another illustration of polymorphism in fungi. 

 The form containing spermatia is known as the 

 spermogonia, while ascophore indicates the state pro- 

 ducing asci. It must not be presumed that two stages 

 or forms only are to be met with. In some species 

 of Sphceria five different conditions have been de- 

 scribed ; the functions of the germ-cells are but little 

 known, the ascophore is looked upon as producing 

 the complete and perfect fruit. S. herbarum common 



on herbaceous stems, is recognised by its multicellular 

 sporidia. S. rostellata flourishes on dead rose and 

 bramble stems, perithecia covered by the bark, which 

 is pierced by the long neck, sporidia arranged in two. 

 rows, each with four nuclei. 



In addition to asci, the hymenium of the ascomycetes 

 gives origin to linear or club-shaped bodies termed 

 paraphyses, which are generally looked upon as 

 abortive asci. Another fungus belonging to this 

 division is very common on the stalk of the bracken, 

 forming long black lines which sometimes nearly 

 cover the surface ; the sporidia are triseptate, the two- 

 central cells larger and filled with greenish granules, 

 the apical cells acute and hyaline ; this is Dothidea 

 Jiliciiia. Cynophallus caninus represents the order 

 Phalloidei, in which the deliquescent hymenium is at 

 first enclosed in a volva or universal covering, com- 

 posed of three layers, the middle one being gelatinous ^ 

 in the present plant when the hymenium approaches 

 maturity the volva is ruptured, and a long pitted, pale 

 orange- coloured stem is rapidly developed ; the 

 hymenium is greenish and slimy, and, mixed with the 

 spores, is either washed off by the rain or devoured 

 by flies, who appear to regard it as a dainty morsel. 

 Most of the plants belonging to this order are remark- 

 able for their fetid odour, the one under considera- 

 tion being the least so. The genus Stcmonitis is 

 known amongst Myxomycetes by the dark stem passing 

 through the plant and giving origin to an intricately- 

 branched capillitium, or web, which is covered with 

 spores ; the investing skin, or peridium, is very delicate 

 and disappears early. S. fusca is not uncommon on 

 rotten wood ; it resembles the reed-mace in miniature, 

 crowded, and springing from a permanent hypothallus 

 or membranous expansion. Calocera viscosa is the 

 very abundant much-branched, viscid, golden-yellow 

 fungus, growing on fir stumps or prostrate fir trunks, 

 the spores are white. Aspergillus glauats is the 

 ubiquitous blue or glaucous green-mould, met with 

 wherever damp organic matter is to be met with. I 

 had this plant in view when I described Mucor mucedo' 

 as " the sage-green mould, common on jam, bread, 

 &c." In Aspergillus there is a creeping septate my- 

 celium, from which spring erect fertile threads, which 

 terminate in rounded heads, from these heads the 

 spores are produced in chains, which are at first 

 arranged in a compact ball and white ; afterwards the 

 chains become isolated and radiate, at the same time 

 assuming a glaucous hue. Penicillium crustaceitm, to. 

 the unaided eye, is indistinguishable from the Asper- 

 gillus, and affects similar situations. On examination 

 the fertile threads will be found more evidently septate, 

 and the top, instead of being globose, terminates in 

 several branchlets, from which spring the strings of 

 round spores, which are not so crowded as in Asper- 

 gillus. The free terminal spore is always the oldest 

 when they are formed in chains, the new ones being 

 developed at the base or fixed end of the chain ; 

 contact with water causes the spores to separate from 



