92 EXPLANATION OF FIGURES IN PLATES. 



[All figures were drawn with the Abbe camera lucida and, with the exception of 

 fig. 30, with the Zeiss apochromatic objective, 2 mm. n. ap. 1.40; figs, i, 3-11, 25, 

 44-47, S5-6i, 65-78 with compens. oc. 8 ; figs. 2, 12-20, 22, 51 with oc. o ; figs. 21, 26-29 

 with oc. 4; figs. 23, 24, 50, 52-54, 59, 62-64, 79 with oc. 12; figs. 31-42, 48, 49 with 

 oc. 18; fig. 30 obj. 8 mm. oc. 8.] 



PLATE I. PHYLLACTINIA CORYLEA. 



FIG. i. Male and female branches; the gametes not yet cut off by septa. 



FIG. 2. Same, showing hyphal cell, from which the oogonium arises, most of 

 the oogonial branch cut away. 



FIG. 3. The oogonial branch coiled around the antheridial branch; the latter 

 septate at the level at which it is constricted by the oogonial branch. 



FIG. 4. The nucleus of the male branch has divided to form the antheridial 

 and stalk-cell nuclei. 



FIG. 5. The antheridium has been cut off from the stalk-cell and lies above 

 and to one side of the apex of the oogonium. 



FIG. 6. Slightly older than stage of fig. 5. Antheridium and stalk partly behind 

 the oogonium. 



FIG. 7. Antheridium and oogonium just before conjugation, the former behind 

 the apex of the latter. 



FIG. 8. Stage of conjugation. The section lies in the plane of contact of the 

 antheridium and the apex of the oogonium. The conjugation-pore is present and 

 appears as a circular opening through the walls of the gametes. The male nucleus 

 is in contact with the larger egg nucleus. 



FIG. 9. Stage of conjugation a little later than fig. 8. The section cuts the 

 plane of contact of the gametes at right angles. The conjugation-pore is open, 

 and through it the protoplasts of the gametes form a continuous mass of cyto- 

 plasm; a large vacuole in the antheridium just outside the conjugation-pore. The 

 pronuclei are in contact; the male nucleus larger than in fig. 8, but still smaller 

 than the egg-nucleus. 



FIG. 10. Oogonium with single large fusion nucleus. Cytoplasm of anther- 

 idium still spongy but containing some granules. 



FIG. n. Oogonium still uninucleated. Wall of antheridium beginning to swell. 



FIG. 12. Oogonium still uninucleated. Wall of antheridium swollen and show- 

 ing strong affinity for orange stain. Early stage of perithecial walls. 



FIG. 13. Egg-nucleus has divided. 



FIG. 14. Ascogonium binucleated. Stalk-cell of antheridium has grown out 

 into a hyphal branch, which curves over the antheridium and is a part of the 

 perithecial wall. 



FIG. 15 a, b. Two sections of the young ascocarp. Antheridium with thick wall 

 and dense content. 



FIG. 16. Slightly older ; perithecial wall becoming two-layered. 



FIG. 17 a, b. Young ascocarp in two sections ; uninucleated cell cut off from 

 the end of multinucleated ascogonium; perithecial hypha is shown arising from 

 stalk of antheridium. 



FIG. 18 a, b. Somewhat older ; end cell of ascogonium separated from the 

 antheridium by crowding in of the perithecial hyphse. 



FIG. 19. Ascogonium with three cells, the next to the last binucleated, the 

 others uninucleated. The whole ascocarp is perhaps dwarfed in this case. 



