xxv.] CORN MILDEW AND BARBERRY BLIGHT. 189 



grass mildew some simple, budding, non-persistent, non- 

 sexual form. 



The Uredo and the Puccinia which follow the jfflcidmm 

 are the reverse of simple, the Puccinia being specially 

 complex and persistent. The Uredo is surely the pupa 

 state of the Puccinia, and Mr. Plowright himself, in 

 describing the teleutospores of the latter, correctly, as we 

 think, terms them resting -spores. Eesting- spores they 

 certainly are, for many of them rest for nearly a year before 

 germination takes place. They are as truly analogues of 

 ova or eggs as are ^Ecidiospores. If Puccinia graminis, 

 Pers., is the larval state of ^Ecidium Berberidis, Pers., it is 

 at least curious that the larvae should be so extremely and 

 continuously prolific in Australia, whilst the sexually mature 

 form is restricted to the other quarters of the globe. 



If the teleutospores of Puccinia are resting-spores or 

 analogues of oospores, as they probably are, the spores of 

 dEcidium cannot be of the same nature without there 

 being two sexually mature egg -producing forms in the 

 same life cycle of the fungus. We lately addressed a 

 question to Dr. T. S. Cobbold, F.R.S., probably our 

 highest living authority on Entozoa, and asked if he 

 knew of any instance in the animal kingdom of a parasite 

 passing two stages of its existence in two different ani- 

 mals, and arising from two different forms of eggs. Dr. 

 Cobbold replied at once : " I give a distinct negative to 

 your question, without prejudice to the proven fact of 

 dimorphism amongst parasites ; and of course also without 

 the slightest reliance on the authority of Meguin, whose 

 erroneous views imply the belief that two sorts of eggs 

 may belong to parasitic conditions of one species." It 

 appears from this answer that the erroneous views of 

 Meguin may be comparable with the views held by many 

 botanists in regard to Puccinia and dStidiwn. 



The change of host plants in fungi has been technically 

 termed hetercecia and metcecia, from heteros, diverse or 

 variable, and meta, a change. 



