DUGGAR. — UREDO POLYPODII. 399 



The disposition of the germ pores thus made clearer is various, and 

 I failed to find any constant number relative to auy special zone. 

 Figures 11, 12, 13, and 14 are examples seen. At most, a study of 

 the germ pores of spores in such immature condition is unsatisfactory 

 on account of the slight differentiation of the walls. 



We may now proceed to a more detailed consideration of what may 

 be the specific distinctions or likenesses in all of the specimens exam- 

 ined. It has been seen that the general characters of the mature spores 

 are the same, the number and distribution of the germ pores varies 

 within certain definite limits, and the process of development shows 

 the same peculiarity — if one may term it such — of thin-walled and 

 thick-walled spores. It remains for a comparison of measurements 

 to lend weight one way or another. As Dietel's results would indi- 

 cate, the form on Cystopteris fragilis is smaller than that on Phegop- 

 teris Dryopteris, but this did not prove entirely constant, nor is the 

 average difference great. The following are the full limits of the 

 spore measurements on the different genera : Phegopteris Dryopteris, 

 Krieg. Fung. Sax. 566, 30-52 X 17-35 /x ; Eriksson, Fung. Paras. 

 Scand. 70 b, 24-40 X 16-35 fx ; Phegopteris Dryopteris, from Germany, 

 26-40 X 18-24 /x ; Cystopteris fragilis, 20-40 X 16-27 /x. One speci- 

 men on Cystopteris fragilis from Massachusetts measured 20-30 X 

 16-21 /x, while another specimen on the same host and from the same 

 State gave 24-40 X 23-27 /x ; thus the extremes on the same host 

 showed a variation quite as marked as that characterizing the forms on 

 different hosts. From these results it seems conclusive that these forms 

 should all be referred to the same species, Uredo Polypodii (Pers.) DC. 



The specimens on Cystopteris fragilis and Polypodium Dryopteris 

 often show a slight roughness on the outer wall, and this character was 

 more clearly seen in fresh specimens of the former. A Uredo on 

 Adiantum Capillus - Veneris from Cavara, Fung. Longobardige, and 

 one on Woodsia glabella from New Hampshire, have this roughened 

 appearance ; but the general characters of the spores seem undoubtedly 

 those of Uredo Polypodii (Pers.) DC. The limited material hardly 

 justifies a positive assertion. A Calif ornian form on Pteris aquilina 

 is distinctly echinulate, but in the general form and size of the spores 

 it agrees with others studied. If it belongs to the same species at all, 

 it is certainly an extreme form.* Fresh specimens are necessary for 

 accurate demonstration. 



* Since the above notes were prepared for publication Dietel has described 

 in Erythea, Vol. II. No. 8, [August, 1894,] Uredo Pteridis D. & H., on Pteris aqui- 

 lina ; and from his description it is plainly the form to which I have referred. 



