Gelehrte Gesellschaften. 
433 
was recoguizable in August, it was not until early in October that 
peridia were developed haying the appearance and microscopic cha- 
racters of b o t r y a p i t e s. 
G. Ellisii. 
June 12. Sporidia sown on detached leaves of 
Pyrus arbutifolia, 
Crataegus tomentosa, 
and kept in a moist chamber. 
June 14. Sporidia sown on 
2 Amelanchier Canadensis. 
2 Crataegus tomentosa. 
June 20. A manifest effect on the Pyrus leaves which, however, 
moulded without actually producing spermogonia. 
June 23. Yellow discolorations appeared where sporidia were sown 
on the Amelanchier plants; otherwise no further result. 
G. c 1 a v i p e s. 
May 11. Sporidia sown on 
3 Crataegus tomentosa. 
3 Pyrus malus. 
2 Amelanchier Canadensis. 
1 Pyrus arbutifolia. 
May 22. Spermogonia appeared on both Amelauchiers, on two fresh 
shoots, as well as numerous leaves, and also upon a single apple 
leaf. Non result with the remaining plants. 
June 3. Signs of aecidia appeared on the young shoots of Amelan- 
chier, one of which died, while the other, 
June 12, produced Roestelia aurantiaca in abundauce. The lea- 
ves affected continued for some time to produce spermogonia, which 
showed a tendency to run along the veins and midrib. 
G. c o n i c u m. 
May 4. Sporidia sown on 
1 Amelanchier Canadensis. 
1 Pyrus arbutifolia. 
3 Pyrus American a. 
4 Pyrus malus. 
May 10 — 11. Spermogonia appeared on the Amelanchier and on 
one apple. 
May 22. Signs of aecidia on most of the A m e 1 a n c h i e r leaves, and, 
May 31, a Roestelia, apparently R. cornuta, was fairly well de- 
veloped. No results with the remaining plants. 
Such, in brief, were the results reached, and at first sight it would 
seem an easy matter, having obtained aecidia from five of the seven 
species of Gymnosporangium, tho refer these, at least, to their 
respective Roesteliae. The task is, however, not so simple, for the 
reason that considerable confusion exists as to the identity and dis- 
tinctions of the species of Roestelia as they occur in nature. 
Of the forms resulting from the present cultures R. aurantiaca 
and botryapites are uumistakable, and cannot be confounded with 
any other New England form, as may be said also of R. transfor- 
mans. With the othcrs, unfortunately, the case is different. Even 
