1889.] BOTANICAL GAZETTE. 213 



have long pedicels which are quite distinct when young, but 

 which tend to gelatinize on the edges as they grow older, 

 especially in the case of the fusiform spores. The thickness 

 of the wall averages about the same in all the spores with 

 the exception of those on the very outside. There it is usu- 

 ally somewhat thicker than in the others (fig. 3) and gener- 

 ally of a smoky-brown color. The contents are alike in 

 both varieties, and in no way different from those of the nor- 

 mal Gymnosporangiam teleutospore, consisting chiefly of a 

 more or less granular mass, in which may be one or more 

 orange oil-like globules and a number of vacuoles. Neither 

 the shape nor distribution of the spores above described is 

 definitely marked, one form gradually passing into the other, 

 with all gradations from the most symmetrically acute vari- 

 ety to the more irregular obtuse one. 



In order to see if, as Kienitz-Gerloff maintained, the 

 acute spores germinated differently from the obtuse ones, I 

 took a considerable number of both forms and studied their 

 method of germination under like conditions. 



When removed to a glass slide and kept moist with a lit- 

 tle water, in a few hours the spores, whether acute or obtuse, 

 produced in the region of the septum from one to three- 

 occasionally four — promycelia of the form typical in this 

 genus, that is, composed of short cells which produce short 

 sterigmata-bearing sporidia (fig. 4). In some cases the 

 sterigmata grew out to an indefinite and often considerable 

 length without producing sporidia. If supplied abundantly 

 with water it not unfrequently happened that, instead of or- 

 dinary promycelia, the germinal tubes grew out to a great 

 length (fig. 5), fifteen or sixteen times the length of the 

 spore, and* the contents did not divide up, but remained con- 

 tinuous throughout without producing sporidia. When the 

 spores are kept onlv slightly damp another peculiarity may 

 be noticed. Instead of growing out into promycelia the 



germinal tubes push out a little distance into short thick fila- 

 ments and then divide into four or five stout oblong cells 

 which soon fall apart (fig. 6). Subsequently the cells which 

 have become thus separated grow out at one or more of the an- 

 gles into hy pha^. An appearance resembling such as has been 

 described has also been noticed by Cramer 5 in the case of 

 G.fuscum. The process may be still further simplified. In 

 some cases the germinal tubes protrude a very short distance, 

 not producing promycelia or a filament of any kind, but only 



*Oeber den Gitterrost der Birnbaunil, etc., Schweiz, landwirth Zeit. 1876. 



