36 PROCEEDINGS OF THE AMERICAN ACADEMY 



In the former case apparentl}'- all of the hyphse bear si:)ermatia, 

 in the latter case only those in the interior of the flask-shaped mass 

 are fertile. The hyphal portion of the spermogonium of Cceoma 

 nitens corresponds then most nearly to the central part of such a 

 spermogonium as is seen in the case of JEcidium herheridis. 



In the above work a verj' convenient and satisfactory stain was 

 fouiid in methylene blue. This was used in a one per cent solution, 

 and the sections were stained on the slide. The sections were first 

 considerably overstained, and then, by treatment with acetic acid, 

 were decolorized to just the point desired. The process of decolor- 

 ization was watched under the microscope and stopped when enough 

 of the stain had been washed out. The acetic acid having been 

 thoroughly gotten rid of, the sections were then mounted in glyce- 

 rine according to the usual method. By means of this decoloriza- 

 tion some differentiation in the staining was brought out, for the 

 acid has a tendency to extract the color from the cells of the host 

 more quickly than from the hyphae of the parasite, so that in a section 

 of the leaf the latter show out much more plainly than they would 

 otherwise have done. In the case of sections cut in paraffin the 

 acetic acid also served to swell up the somewhat shrunken tissues 

 to a more natural appearance. 



EXPLANATION OF FIGURES. 



Fig. 1. A very early stage of the spermogonium. 

 " 2. A slightly more advanced condition, but before the hyphge have any 



definite arrangement. 

 " 3. Showing the splitting apart of the walls of the epidermal cells, and also 



the parallel arrangement of the hyphse in the young spermogonium. 

 " 4. a, showing the rupture of the walls by the hyphae. b, a more advanced 



stage, where there is only a trace of the dividing wall left. 

 " 5. A mature spermogonium with only one row of supporting cells. 

 " 6. A mature spermogonium with the normal two rows of supporting cells. 

 " 7. Horizontal section of mature spermogonium. 

 " 8. Hyphae from spermogonium showing formation of spermatia. 

 " 9. a, b, c. Haustoria. 



Figures 1 to 7 X 425 diameters ; Figures 7 and 8 X 650 diameters. Figures 

 1 to 4 drawn from sections of alcoholic material ; Figures 5 to 9, from fresh speci- 

 mens. All figures drawn with Abbe camera. 



June, 1892. 



