672 



APPENDIX. 



CONSTANCY AND MUTABILITY OF THE SPECIES OF FUNGI. 



Are there SPECIAL importance has recently been attached to the 

 tion whether the species and varieties of the lower 

 which have as yet been looked on as distinct, are 



chracters for really of constantly distinct form and possess constant 

 species of physiological characters, or whether the morphological 

 and biological characteristics which are employed for 

 distinguishing the species are varying and inconstant 

 attributes, which readily undergo permanent alteration 

 under the influence of the external conditions of exist- 

 ence. 



For the solution of this question we may possibly 



obtain information from comparison with the higher 



plants, which form useful analogies as regards the con- 



stancy or variability of species and their characteristics. 



Behaviour of We cannot, however, come to a true decision by such 



organisms. comparison : this can only be arrived at by direct inves- 



tigation. 



As a matter of fact, it has long been known that a 

 number of morphological and biological alterations can 

 be observed in all plants. In the first place, certain 

 alterations are constantly seen in all normal plants of 

 the same species ; these belong to the characteristics of 

 the species, and only complete its special characters. 

 To this class of alterations belong those which the plants 

 show at various stages of their growth and development ; 

 further, the alternation of generation of the fungi, with 

 its enormous differences in form and physiological cha- 

 Differences in racters. Where the developmental cycle of a species 

 development. nas no ^ J 6 ^ t> een completely ascertained, it may readily 

 happen that various developmental forms of the same 

 species may for a time be looked on as independent 



