1 8 Massee : The Modem Method of Studying Agarics. 



that separate one species from another. One method is rule-of- 

 thumb, the other scientific. 



Another feature too obvious and general to escape attention 

 was the fact that in the case of large genera distributed 

 throughout Europe, the extra British species could be sand- 

 wiched between British species. What I exactly mean is this, 

 supposing three British species to be characterised by three 

 characters each, represented by i, 2, 3 ; 4, 5, 6 ; 7, 8, 9 respec- 

 tively, then we find three extra British species characterised 

 respectively by some other combination of these same characters, 

 thus, I, 3, 4; 2, 4, 7 ; 3, 8, 9, etc. This point was illustrated 

 more clearly by means of coloured diagrams of British and 

 exotic species of Lepiota. 



In the majority of even the largest genera of Agarics there 

 are not more than half a dozen constant specific points of dis- 

 tinction, and it is the correlation of two or more of these 

 characters that constitute a species. Consequently when these 

 distinctive features of a genus are once evolved, it seems 

 possible to have as many species produced as there are possible 

 combinations of the primary factors. 



Now the above significance of the term species, as under- 

 stood by students of the Agarics at the present day, opens up 

 a wide field which can only just be alluded to at present. 



Briefly it means that the species of Agarics are not of the 

 same value as the species of Phanerogams or of the higher 

 animals. In the latter each species, in addition to bearing the 

 generic marks, possesses at least one specific mark peculiar to 

 itself, in addition to the variously modified marks characteristic 

 of allied species. 



In Agarics this is not the case, the species having no indi- 

 vidual special characters, but are made, as described above, by 

 the varied combinations of generic characters. 



Hence genera, or sections of large genera in Agarics, are 

 only equivalent to species of the higher plants and animals, 

 whereas the so-called species of Agarics are merely forms of 

 such genera or sections, slowly approaching the status of 

 species in the higher sense, but as a rule yet lacking the hall- 

 mark of a true species in the absence of specialised individual 

 characters. 



Such species in the process of evolution fit in beautifully with 

 the views of De Vries, expressed in his celebrated work on the 

 theory of species formation by mutation ; and it is certain that if 

 this celebrated botanist had been a mycologist he would have 



Naturalist, 



