36 British Ftmgi. 



made to produce the Puccinia stage by sowing tliem 

 on wheat leaves in the autumn, and the Puccinia 

 spores, if kept until the following spring- and then 

 placed on a barberry leaf, in turn produce the ^cidium 

 stage, the spores of which when placed on wheat 

 leaves, commence the cycle afresh by giving origin to 

 the Uredo stage. The complete fungus, including the 

 three forms, is now known as Puccinia graminis. Al- 

 though the above sequence of forms is what may be 

 termed the normal order of things in the development 

 of the species, yet it has been shown that the existence 

 of the species is not dependent on the rigid following 

 out of this sequence. It is well known that the spores 

 of the Uredo form w^hen sown on wheat, and also some 

 other grasses, give origin to a similar Uredo form 

 during the summer months, and further, that under 

 certain unknown conditions the Uredo and Puccinia 

 forms can reproduce themselves for several years in 

 succession, without the intervention of the ^cidial 

 form ; hence, although proved beyond doubt that the 

 forms above given belong to one species, yet we are 

 not thoroughly acquainted with the relative impor- 

 tance of the several forms as affecting the existence 

 of the species, in other words, we do not know its 

 complete life-history ; and it is not saying too much 

 to state that we are not at present acquainted with all 

 the possibilities involved in the life-history of any 

 one fungus. Nevertheless, much is known in this 

 direction, and new observations are being daily added 

 to the stock of information. Undoubtedly mistakes 

 and misinterpretations are made, as would naturally 

 be expected in connection with such investigations,, 



