BY D. McALPINE. 467 



and teleutospores, but on this view they ought to be more general 

 and not confined to individual species. 



P. Magnus* considers, on the other hand, that the uredospores 

 have developed out of teleutospores on account of their better 

 adaptation for germination and dissemina.tion, and that those 

 species which have no uredospores never acquired the property of 

 forming them. 



Dr. Plowrightf considers them as morphologically analogous to 

 the teleutospores of Uromyces, somewhat similar to the view of 

 Tulasne,! who regards them as reduced teleutospores, the reduc- 

 tion being brought about by the abortion of the lower cell and 

 thus the genus Uroniyces, characterised by such spores, is to be 

 considered a degraded form of Fuccinia. There are other con- 

 siderations, however, such as the nature of the host-plants, which 

 would seem to point to the Uromyces as being rudimentary and 

 not reduced forms of Puccinia. 



In Puccini pruni, Pers., the two cells of the teleutospores 

 readily separate and the lower cell is often imperfectly developed, 

 so that the connection between Uromyces and Puccinia seems to 

 be shown here. In fact, it would appear that even the eminent 

 mycologist Dr. Cooke was misled by this resemblance when he 

 named this very species, sent from Australia on peach and 

 almond leaves, as Uromyces amygdali. And if this relationship 

 is accepted, then the term mesospore, as indicating a transition- 

 form between two other kinds of spore, is inappropriate, as it is 

 really between the two genera. 



Just as the unicellular or Uromyces-\\\ie spore links the 

 Puccinia on to lower but not necessarily earlier forms, so the 

 multicellular spore foreshadows the more advanced forms of the 

 Uredines, such genera as Triphragmium in which the teleutospore 

 is normally three-celled, and Phragmidlum, in which it may 

 consist of from three to ten superimposed cells. And thus close 



* Ker. Deutsch. Bot. (4esell. ix. (1891). 

 + Brit. Ured. and Ustilag. p. 39 (1889). 

 : Ann. Sci. Nat. 4 Ser. Vol. ii. p. 145 (1851). 

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