320 PROCEEDINGS OF THE AMERICAN ACADEMY 



less drawn definite conclusions with regard to the connection between 

 certain teleutosj^oric and ajcidial forms. 



Finally, it may be urged that, in all the cases where spermogonia 

 followed the sowings of sporidia, their development was not a result 

 of the sowings, but proceedeil from the mycelium of some Roestelia 

 already in the material used. That this was the case in the shoots of 

 Amelanchier and P. arhutlfuUa I think was probably true, and the 

 same may have been true in case of the C. tomentosa, although I 

 am not prepared either to admit or deny the fact. Admitting the 

 theory of previous infection, however, how are we to explain the 

 case of the C oxyacantha, on the leaves of which spermogonia abun- 

 dantly followed the sowing of the sporidia of G. glohosum, but did not 

 appear after the sowing of other species ? I must admit that I am 

 much perplexed to explain the frequency of spermogonia in some 

 cases and their absence in others, and the failure of infected seed- 

 lings to develop aecidia, or even to show the least traces of them. I 

 should be the last to claim that my experiments were in any sense 

 conclusive, but, on the contrary, recognize their incompleteness, and in 

 some respects their contradictory character. INIy cultures are only sig- 

 nificant in so far as they show more plainly dilhculties to be avoided, 

 and the general direction in which one must work to reach a successful 

 result, if such a result is ever to be reached, iu the study of the devel- 

 opment of our Gymnosporangia. 



In Appalachia, Vol. III. pp. 239-243, I gave an account of the 

 Peridermia of the White Mountains, and stated that the species which 

 occurs on the dwarf form of Abies nigra resembles P. ahictinum 

 (A. &. S.), which has in Europe been associated with Ckrysomyxa 

 RJiododendri and C. Ledi as an secidial form. At the time of my 

 visit to the White Mountains, in August and September, no species of 

 Uredinece was found either on Rhododendron Lapponicum or Ledum 

 latifolium. As Mr. Edwin Faxon was about to make a botanical ex- 

 cursion to the White Mountains in June and July of 1884, I asked 

 him to examine the Rhododendron and Ledum on Mt. Washington, 

 to ascertain whether a Ckrysomyxa occurred on those hosts early in 

 the season. With his accustomed acuteness, Mr. Faxon succeeded in 

 finding a form on Ledum, which appears to have been common in some 

 Fpots in July, but which rapidly disappeared, as the early specimens 

 had an abundance, and the later but little, of the fungus. I visited 

 the locality at the head of Tuckerraan's Ravine, where the fungus 



