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TEXT-BOOK OF FUNGI 



Perhaps nowhere else in the whole range of fungi has 

 such extreme differentiation, both morphological and 



FIG. 98. Mclampsora pinitorqua, a fungus whose aecidiospores are pro- 

 duced in chains, i, top of a young pine attacked by the aecidial form of 

 the fungus ; 2, three chains of aecidiospores in different stages of develop- 

 ment ; 3, an aspen leaf with pustules formed by the teleutospore stage of 

 the fungus ; 4, section through a pustule or sorus of teleutospores, as yet 

 covered by the epidermis of the leaf. Figs, i and 3, rather less than nat. 

 size ; the remainder mag. 



physiological, taken place as in the genus Puccinia, ex- 

 pressed by such terms as heteroecism, biological forms, 



