6 INTRODUCTION 



either directly or indirectly by an act of fertilisation, reserving the term 

 ' gonidium ' for those which are produced without any previous act of 

 impregnation. It is obvious that one practical defect of this last sug- 

 gestion is that it may necessitate a perpetual change of terminology as 

 our knowledge advances. Every fresh extension of the domain of sexual 

 fecundation— and it is probable that many such will take place — will 

 involve the removal of a fresh series of reproductive cells from the cate- 

 gory of gonidia to that of spores, even though they may not be the 

 immediate result of an act of fertilisation. Again, if the spores of ferns 

 and mosses are the indirect result of impregnation, it is difficult to say 

 why the term should not ultimately include all reproductive bodies 

 whatever, except the spores of the ' apogamous ferns ' with which Farlow 

 and de Bary have recently made us acquainted, and of other similar 

 abnormal productions, which are certainly not the result of impreg- 

 nation, direct or indirect. 



It seems a sounder principle — and is certainly more convenient to 

 the student— to base a system of terminology on facts which can be 

 confirmed by actual observation, rather than on unproved hypotheses. 

 We propose, therefore, as the basis of our terminology, to restore the 

 term spore to what has been in the main hitherto its ordinary significa- 

 tion, and to restrict its use to any cell produced by ordinary processes of 

 vegetation, and not directly by a union of sexual elements, which becomes 

 detached for the purpose of direct vegetative propagation. The spore may 

 be the result of ordinary cell-division or of free-cell-formation. In 

 certain cases {zoospore") its first stage is that of a naked primordial mass 

 of protoplasm. In rare instances it is multicellular, breaking up into a 

 number of cells {polyspore, composed of merispores, or breaking up into 

 sporids). 



The simple term spore will, for the sake of convenience, be retained 

 in Muscinese and Vascular Cryptogams ; but in the Thallophytes it will 

 generally be used in the form of one of those compounds to which it so 

 readily lends itself, expressive of the special character of the organ in 

 the class in question. Thus, in the Protophyta we have chlamydo- 

 spores ; in the Myxomycetes, sporangiospores ; in the Saprolegniese and 

 many Alg», zoospores ; in the Uredinese, teleutospores, actdiospores^ 

 uredospores, and sporids ; in the Basidiomycetes, basidiospores ; in the 

 Ascomycetes (including Lichenes), ascospores, polyspores, a.nd merispores ; 

 in the Diatomacese, auxospores ; in the CEdogoniaceas, androspores ; in 

 the Florideae, tetraspores ; and others belonging to special groups. 

 The cell in which the spores are formed will, in almost all cases, be 

 called a sporange ; and this term will be compounded in the same way 

 as spore. 



