INTRODUCTION. 1 3 



There are a series of phenomena classed together under the 

 name of polymorphism, dualism, dimorphism, which form a 

 cycle of development of different kinds of spores. For instance, 

 the ^cidium berberidis, growing on the barberry bush, pro- 

 duces spores which will only germinate on the graminae vegeta- 

 tion, producing the well-known wheat rust (Trichobasis rubi- 

 vera), and yet that does not complete the cycle : it requires a 

 third kind of spores called puccinia spores, or brand spores, 

 which in turn will only germinate on the barberry bush leaves. 



It requires three different kinds of spores to complete a 

 fully developed plant, i. ^cidium ; 2. Uredo, and 3. Puc- 

 cinia spores ; the latter are called teleuto or winter spores, for 

 they carry them through the winter in the form of brand. 



You will meet with a number of instances of polymorphism, 

 or dualism, in the fungi group. Dualism is of frequent occur- 

 rence in the Coniomycetes or Hypodermea of the Germans. 

 It is quite certain that a large portion of the so-called species 

 of Phoma, Cytispora, Septoria, Diplodia, are mere cases of 

 dualism. All are interesting, so far as ascertained dualism is 

 concerned ; or as far as there may be a prospect of showing that 

 they are the spermagonia of the ascophorous pyrenomycetous 

 fungi. 



There is no class of vegetation which shows so much wisdom 

 in the display of organs for the purpose of the perpetuity of its 

 kind as fungi do. 



The minute dust-like spores, which are always in danger of 

 being destroyed even by the morning dew, has provisions 

 made almost as soon as born to form a fresh mycelium pene- 

 trating the stomata of a green leaf, there to perfect itself to 

 form a nidus for a more permanent progeny. We mycologist 

 can not help but exclaim with the Psalmist, " Marvelous and 

 wonderful are Thy works, O Lord of hosts : in wisdom hast 

 Thou made them all." 



