xxv.] CORN MILDEW AND BARBERRY BLIGHT. 197 



each other, without being related, in the most complicated 

 and bewildering manner. 



In the case of Puccinia violarum, Link., where the 

 Uredo, as well as ^Ecidium violce, Schtmi., all occur on the 

 same host, the three forms have been accepted as differ- 

 ent conditions of one parasite ; but when Mr. Vize detected 

 a second species of dEcidium on white garden violas, and 

 named it 2s. depauperans, a difficulty arose, for there were 

 then two ^cidia and only one Puccinia. 



We dissected and illustrated the original examples as 

 found by Mr. Vize in the Gardeners' Chronicle for 1 6th Sep- 

 tember 1876, p. 361. Mr. W. B. Grove, M.A., has re- 

 cently published a note regarding the second viola ^Ecidium 

 in the Journal of Botany, vol. xxi. p. 274. In this paper 

 the author states that he has detected the Uredo as well 

 as the Puccinia condition of ^Ecidium depauperans, Vize, on 

 violas ; and he describes the Puccinia as a new species under 

 the name of P. cegra ; the dEcidium appears at the end 

 of May and the Puccinia in August. Mr. Grove gives no 

 proof that the Puccinia is connected with the ^Ecidium ; 

 he believes they are connected because the three forms he 

 describes grow on the same plant. We have just shown 

 that in several instances it is acknowledged that jtEcidium 

 is not always assumed to be genetically connected with a 

 Puccinia when the two forms grow in company on the 

 same plant. Mr. Grove appears not to have experimented 

 with pro-mycelium spores. 



The disparity in the number of species found under 

 j^Ecidium and Puccinia is great ; but the disparity is of 

 no moment if it is acknowledged that one form can go on 

 reproducing itself for an indefinite time without aid from 

 the other. 



Besides the Puccinia violarum, Lk., and P. cegra, Gr., 

 there is a P. violce, D.C., and a P. violce, Schum. 



In conclusion, one more point must be adverted to. We 

 have shown that plants invaded by Puccinia and ^Ecidium 

 carry an hereditary disease by which they are saturated, 



