2G8 FUNGI. 



which have followed those grains wherever they have been 

 distributed, and the potato disease, which is said to have been 

 known in the native region of the potato plant before it made 

 its appearance in Europe. We might also allude to Puccinia 

 malvacearum^ Ca., which was first made known as a South 

 American species ; it then travelled to Australia, and at length 

 to Europe, reaching England the next year after it was recorded 

 on the Continent. In the same manner, so far as we have the 

 means of knowing, Puccinia Apii, Ca., was known on the Con- 

 tinent of Europe for some time before it was detected on the 

 celery plants in this country. Experience seems to warrant the 

 conclusion that if a parasite affects a certain plant within 

 a definite area, it will extend in time beyond that area to 

 other countries where the foster-plant is found. This view 

 accounts in some part for the discovery of species in this country, 

 year after year, which had not been recorded before ; some 

 allowance being made for the fact that an increased number of 

 observers and collectors may cause the search to be more com- 

 plete, yet it must be conceded that the migration of Continental 

 species must to some extent be going on, or how can it be 

 accounted for that such large and attractive fungi as Sparassis 

 crispa, Helvellas gigas, and JULorchella crassipes had never been 

 recorded till recently, or amongst parasitic species such as the 

 two species of Puccinia above named ? In the same manner it 

 is undoubtedly true that species which at one time were common 

 gradually become somewhat rare, and at length nearly extinct. 

 We have observed this to apply to the larger species as well as 

 to the microscopic in definite localities. For instance, Crater- 

 ellus cornucopioides some ten years ago appeared in one wood, 

 at a certain spot, by hundreds, whereas during the past three or 

 four years we have failed to find a single specimen. As many 

 years since, and in two places, where the goafs-beard was abun- 

 dant, as it is now, we found nearly half the flowering heads 

 infested with Ustilago receptaculorttm, but for the past two or 

 three years, although we have sought it industriously, not a 

 single specimen could be found. It is certain that plants found 

 by Dickson, Bolton, and Sowerby, have not been detected since, 



