1 68 BOTANICAL GAZETTE. [Jul}*' 



March 28, Spermogonia appeared abundantly on all the infected 

 plants. These were then watched carefully for three months, at the ex- 

 piration of which, 



June 19. iEcidia began to appear on the leaves of the Crataegus, while 

 the apple showed swellings beneath the spots of spermogonia. These 

 swellings began slowly to produce secidia, having, as far as could be 

 judged, the characters of " lacerata z" but 



July 7. The leaves suddenly turned yellow and fell off, while at this 

 date "lacerata y" was abundantly developed on the Cratxgus. 



" G. CONICUM." 



Two plants of Amelanchier were sown with sporidia of the "birds- 

 nest" Gymnosporang ium for class illustration on May 12, spermogonia ap- 

 pearing in about a week (the exact date not noted), and during the sec- 

 ond week in June a Roestelia, similar in all respects to that obtained in 

 the previous years, was well developed upon the stems and leaves. 



The cultures of 1887-88, then, agree with the results of 

 the previous year in all respects so far as the secidia obtained 

 from the corresponding Gymnosporangia is concerned, and 

 supplement them by the addition of the a^cidial form of G. 

 globosum, the relation of which to any recidial form has here- 

 tofore been a most perplexing question. The cultures estab- 

 lishing this relationship which were made in 1888 were, it 

 will be noticed, conducted with the greatest care. The fun- 

 gus and its host were forced in a greenhouse, and the infec- 

 tion made more than six weeks before it would naturally 

 have occurred out of doors, and the plants were constantly 

 examined during the whole period from infection to the pro- 

 duction of secidia. No other species of Gvmnosporangium 

 was brought into the greenhouse, and when the season for 

 the natural development of the fungus out of doors had ar- 

 rived, the possibility of infection from without was past. 

 There is, therefore, no shade of doubt connected with the 

 experiment, the result of which is, moreover, supported by 

 the results obtained in the more careless cultures of the pre- 

 vious year. Although in the present instance the culture on 

 apple was not carried as far as could have been desired, I 

 think it may be safely assumed that both "lacerata y " and 

 "lacerata z" are a^cidia of G. globosum. This conclusion is 

 somewhat of a surprise, since G. globosum has been consid- 

 ered a very near ally of the European G. fuscum, of which 

 it was originally described as a variety. The axidium of G. 

 fuscum, on the other hand, is stated definitely by Mr. Plow- 

 right to be R. cancellata ; a conclusion in harmony with the 



