Si 



ROTA.Ii IIOHTTCULT URAL SOCIETY. 



XVI. Provisional account of some observations proving that 

 Rodisoma Sabinw, which grows on the branches of Juniper us 

 Sabina, and Roestelia eancellata, which attacks the leaves of Pear- 

 trees, are alternate generations of the same species of Pungus. 

 By A. S. Ousted*. Copenhagen, June 10, 1865. 



As long ago as 1862, I suspected the existence of the above- 

 mentioned relation between these two fungi, which have hitherto 

 been classed in different genera and different families. In that 

 year I noticed in a garden, for the first time, specimens of Rodi- 

 soma Sabince, which spread their beautiful tongue-shaped tremelloid 

 orange-red tufts in great abundance over some plants of Junipents 

 Sabina ; and in the course of the same summer I observed, also 

 for the first time, in the same place, Roestelia eancellata, which up 

 to that time had not occurred there. In the interval I caused a 

 Savin infected with the Rodisoma to be planted in the Botanic 

 Garden, so as to be able another year to make observations upon 

 this interesting fungus. The next year Roestelia eancellata, which 

 had never been seen before in the Botanic Garden, appeared 

 there for the first time, but, as is worthy of remark, only upon 

 the pear-trees nearest to the juniper. 



The simultaneous appearance of these two fungi in two different 

 places attracted my attention, but at first I thought it was omy 

 an accidental occurrence. 



However, as M. de Bary had shown that alternations of genera- 

 tions occurred in analogous fungi (subject, no doubt, to the con- 

 dition that the two generations should grow upon the same 

 species of plant, or at least upon a species of the same family, as 

 is the case, for instance, with the sporidia of TJromyces Rabce, which, 

 on the leaves of the bean, produce JEeidium Leguminosarum, the 

 spores of which in their turn reproduce, upon the same plant, 

 TJromyces Fabce), and as I had learnt that in other places gardeners 

 were of opinion that Roestelia eancellata was never seen except 

 after the appearance oi Rodisoma Sabince, I no longer doubted that 

 these two fungi were the product of an alternation of generations ; 

 but the point was to prove it experimentally. This is the object 

 of the little experiment which I have just undertaken, and by 

 which it has been for the first time demonstrated that the two 

 alternate generations of one and the same species of fungus grow 

 upon two plants belonging to very different families. 



On the 18th of May I placed some sporidia of Rodisoma, already 



* Translated by F. Carrey, Esq., F.L.S. 



