308 KECORD OF CURRENT RESEARCHES RELATING TO 



cultivated onion from some wild species where it has not yet been 

 detected. 



M. Cornu enumerates also the other diseases to which the onion 

 is subjected, viz. : (1) the disease known as "la graisse," by which 

 in wet seasons and in certain soils the whole substance of the onion 

 becomes oily and foetid ; this is generally accompanied by the appear- 

 ance oi Peronospora Schleideniana ; (2) a Cladosporium which produces 

 black spots, but is not serious. 



.fficidium abietinum.* — Professor De Bary has made a careful 

 examination of this fungus, found throughout the Alps on the spruce 

 fir, from an altitude of 1000 metres to the upper limit of the tree. It 

 is found only on the shoots of the present season, the aecidium fruits 

 appearing on the leaves in the form of cylindrical or usually flattened 

 tubes, of a pale red colour, projecting to a height of 1 mm. above the 

 surface, and with quite the ordinary structure of the Uredineae. When 

 the fecidium fruits are mature, the spermogonia are visible as brown 

 spots on the surface of the leaf. The parasite, widely distributed 

 through the Alps, is not found in other similar situations, as the 

 Vosges, Black Forest, &c. A careful examination shows that the 

 tissue of other non-infected jmrts of the tree is not infected by the 

 mycelium of the parasite ; while the spores readily germinate into a 

 curved filament. From this it is seen that the fscidium must be 

 brought to the foliage of the pine in some other form ; and analogy 

 indicates that this would be in the form of teleutospores. The only 

 teleutospore-form at present known on the pine is that described 

 under the name Chrysomyxa Abietis, which does not produce secidia. 

 The fecidium of the spruce fir is therefore clearly a heteroecious or 

 dioecious species. 



In pursuing this inquiry it struck Professor De Bary that the 

 JEcidium abietinum was found only in those districts marked by the 

 presence of Rhododendron fernigi^ieum or hirsutum. The uredo-form 

 common on these species, Uredo Rhododendri, had however not been 

 known to produce teleutospores. But in July, 1878, Dr. Blytt brought 

 from the Great Scheideck leaves of B. ferrugineum, on the under side 

 of which were uredo-pustules producing abundance of teleutospores ; 

 and they were subsequently found abundantly in the same situation 

 in the early spring. From this situation they undoubtedly reach the 

 young shoots of the pine, and germinate in the well-known fecidium- 

 form. The aecidiospores are disseminated when rijpe in immense 

 quantities, and easily again reach the rhododendron. 



Albertini and Schweinitz have described the A. abietinum as 

 occurring on the spruce fir in the neighbourhood of Ledum palustre, 

 which again is attacked by a uredo-form Uredo Ledi. These two 

 uredos show considerable differences from one another, but whether 

 specific or only induced by growing on a different host, De Bary is at 

 present unable to decide. 



With regard to the systematic position of the fungus, De Bary 

 considers it very nearly allied to the other parasite of the spruce fir 



* ' Bot. Zeit.,' xxxvii. (1879) p. 761. 



