Hick : The Sexual RErEODUcxiox of Fungi. 



89 



ascospores. In neither group do we as yet know of any sexual process 

 of propagation, and we may therefore pass on at once to the 



Zygospores. The fungi placed in this class are grouped into two 

 orders, Myxomycetes, or Myxogastres, and ZygomyQeU^s, in both of which 

 examples of sexual reproduction are met with. As might have been 

 expected, however, from the simple structure of the organisms concerned, 

 the process is by no means a complicated one, and is altogether wanting 

 in some of the features usually regarded as essential. 



Myxomycetes. The life-history of the Myxomycetes is in many respects 

 so peculiar, and their outward aspect, at certain stages, so different from 

 that of most plants, that by some naturalists they have been excluded 

 from the vegetable kingdom, and have been treated as animals. But the 

 best authorities now regard them as forming a distinct group of plants, 

 which in the absence of chlorophyll, in the function of nutrition, and the 

 mode of formation of their spores, have close affinities with the fungi. 

 Many of them, such as the Arcyrias, Physarums, Stemonites, and 

 Trichias, are common in the autumn on old decayed stumps, where they 

 may often be gathered in all stages of development. Several of these 

 form a peculiarly constructed sporangium containing a capillitium of 

 closely meshed or free threads, among which a large number of small 

 spores are produced. The sexual process, which is here termed " conju- 

 gation " on account of the similarity of the uniting masses of protoplasm, 

 is effected by the contents of the spores, and may be described generally 

 as follows : — 



The spores having been scattered by the rupture of the structureless 

 walls of the sporangium and the elasticity of the capillitium, are capable 

 of germination as soon as the requisite warmth, moisture, and a suitable 

 substratum are obtained. Should these conditions be wanting, their 

 vital activity will remain inactive a considerably time, without being 

 entirely lost. On germination the spores do not form any structure 

 comparable to the mycelial threads so commonly produced by fungus 

 spores, but the cellulose coat ruptures, and the protoplasmic contents 

 come out in a naked condition, and, as is usual with free fragments of 

 protoplasm, assume a more or less globular form. Losing this after a 

 short time, and becoming elongated and somewhat tapering at one 

 extremity, the protoplasm develops a fine cilium and moves about like an 

 amoeba. In this condition it lives for a little while, absorbing nourish- 

 ment, increasing in bulk, and even multiplying by division, and may be 

 conveniently spoken of as a zoospore. But by-and-by the nucleus dis- 

 appears, the cilium is lost, the amoeboid movements become sluggish, the 

 dividing process comes to an end, and a contrary one sets in. Two, 

 three, or more of these amoebi-form zoospores coalesce or " conjugate," 



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