STRICKLAND: NOTES ON FUNGI. 185 



perhaps among the minute Pezizre and Sphaeriae, where the cups and 

 perithecia are often very minute and very much alike in the different 

 species. Most of the spores and sporidia have now been measured, 

 the relative sizes are therefore known, and sketches made under the 

 same object-glass will show the relative size with sufficient accuracy 

 for determination, when coupled with the differences in the form of 

 the asci, paraphyses, and sporidia, together with septation and colour. 

 Let us suppose a herbarium in which the whole series of Ascomycetous 

 fungi is complete, each specimen being good and abundant, with a 

 sketch of the fructification, ascus, paraphyses, and sporidium, the 

 colour of the latter being noted and the power of the object-glass 

 used in delineation. The specimen to be identified, I assume, has 

 been similarly treated. All the elements for a precise determination 

 will now be present. The relative size of the sporidium can be 

 observed by comparing it with that of some well-marked species, 

 such as Sphceria pulvis-pyrins, of which the size can be discovered 

 by reference to the handbooks. The sketch of the fructification can 

 then very easily be compared with the sketched fructification of the 

 specimens in the herbarium; this, together with the difference in the 

 host and the growth and form of the perithecia or, in the case of 

 the Pezizae, of the cups, will in most cases suffice for a complete 

 identification and the specimen will fall into its proper place in the 

 herbarium. 



The difficulty of identification may also be looked at from another 

 point of view. I have already noted that the species of fungi being, 

 very many of them, parasitic on comparatively recent species of 

 phanerogams, must be themselves comparatively recent, and that 

 from the immense variety of forms which characterises this group of 

 cryptogams, and their wide diffusion, we may infer that they are, like 

 the host they grow upon, themselves liable to considerable variation. 

 Here, then, we have the process of species-making going on before 

 our eyes in comparatively simple organisms, and one may be permitted 

 to hope that here, if anywhere, some of the causes which are at work 

 to produce species should be, so to say, caught in the act. To the 

 evolutionist, therefore, the fungi ought to be a particularly interesting 

 subject of study. The famous phrase, 'the survival of the fittest,' 

 perhaps covers a larger field than was at first consciously realised ; 

 certainly it means the survival of the fittest to exist, and the survival 

 of those forms which fit themselves into and thrive within the spare 

 and hitherto unoccupied holes and corners of the great mansion- 

 house of mother nature. 



We have in fungi a number of highly variable forms built upon a 

 simple pattern, yet exhibiting an astonishing diversity; and moreover, 



June 1889. 



