130 DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



In this system of nomenclature the gonidium (3) for example of Oedogonium 

 and Vaucheria would be a swarm-spore (2) ; the oospore of these genera would be 

 non-motile spores, like the zygospore of Spirogyra ; but the zygospore of Aceta- 

 bularia and Botrydium is a swarm-spore, and all oospores are at the same time 

 carpospores, and so on. The terminology indicated under 3 apparently comes so 

 near to that of Sachs, that the question may be asked why the latter should not be 

 accepted as the foundation of the system ; it will be well therefore to point out once 

 more the fundamental distinction between Sachs' terminology and that now proposed. 

 With Sachs spores and gonidia stand side by side as different things ; in this work 

 carpospores and gonidia are special phenomena subordinated to the general con- 

 ception of the spore. On practical grounds, which have been to some extent 

 already indicated and which will be further explained below, as under the Basidiomy- 

 cetes, we cannot do without a word to express this general conception as defined above. 

 The terminology here proposed is therefore by no means unnecessary, as it might 

 appear to be if we confine our attention to Ferns, Mosses, and some types of 

 Algae. 



The terminological sketch which has now been given supplies a scheme which is 

 drawn from actual phenomena forming the general rule, and is applicable to them. 

 But the highly complex reality is not designed after a single scheme ; there are inter- 

 mediate forms connecting phenomena which are separated in the scheme, exceptions 

 to the rule, and no terminology can take all these exceptions equally into account. 

 In such cases the systematic terminology must necessarily be modified to suit the 

 particular occasion. This must not be forgotten either here or in connection with 

 the objects which will be described in the succeeding chapter. 



A spore proceeds to a further development if the conditions are favourable. 

 The commencement of this further development is termed germination. Germina- 

 tion considered morphologically consists in a very large majority of cases in the 

 construction of the vegetative body of a unit-bion, as for example when Fungus- 

 spores put out germ-tubes, as described above in section XXXI. But there are 

 other cases also. Not only are there those in which the plantlet growing from a 

 spore remains a rudiment morphologically and in this condition is devoted to 

 special functions, as in the germinating androspores of heterosporous Pteridophytes 

 or the pollen-spores of flowering plants, but there are others in which the germinating 

 spore produces other spores directly as daughter-cells and is entirely expended in 

 forming them, as was described above in section XXXI in the case of certain Fungi. 

 In other words in such cases the germinating spore becomes the mother-cell or 

 receptacle of spores of the next higher generation, a sporangium, as such receptacles 

 are generally termed. The same object viewed in the different relations specified 

 above may equally well be called a spore or a sporangium. The same thing may 

 occur in spores of the most different morphological value, as in the oospores of 

 1 Oedogonium and Sphaeroplea and in the gonidia of Cystopus. Spores which are 

 strictly homologous and come from nearly allied species may develope, some as 

 sporangia, others as a rudimentary thallus ; for example, the gonidia of Peronospora 

 (section XXXVII), the oospores of Oedogonium on the one hand and on the other 

 those of Vaucheria. The homology between the spore-forming oospore of Oedogonium 

 and the sporocarp of a Moss has been already pointed out, and the former may 



