BIOLOGY OF ALEURODISCUS 457 
EXPLANATION OF PLATES 
Plate XXXI 
Upper figure: Aleurodiscus amorphus on Abies twigs. 3^ natural size. 
Middle: Same, natural size. 
Lower: Aleurodiscus Oakesii on hark of living Ostrya. Natural size. 
Plate XXXII 
Figures i-ii, X 12. Figure 12, X 84. Figure 13, X 440. Figures 14-16, X 390. 
Fig. I. Section of bark of Abies with a stroma of pseudoparenchymatous tissue of 
Aleurodiscus amorphus, the primordium of a fruit body. 
Fig. 2. Two similar primordia somewhat further advanced. 
Fig. 3. A fruit body that has broken through the outer layers of bark and a smaller 
one about to emerge by its side. 
Figs. 4-6. Further development of the same. In the fruit body shown in figure 6 
the hymenium has begun to develop. 
Fig. 7. Pezizoid type of fruit body. The numerous thin white hyphae on its sides 
and margin give it a tomentose appearance. 
Fig. 8. Two confluent fruit bodies. 
Fig. 9. Fruit body with three stromata of Tremella sp. growing upon it. 
Fig. 10. Later stage of a similar fruit body, the Tremella having entirely covered the 
host. The hy menial layer of globose basidia appears as a border of black dots on the upper 
surface. 
Fig. II. Similar to preceding. 
Fig. 12. Section of hymenium of Aleurodiscus amorphus showing basidia and para- 
physes. One older basidium is seen with two sterigmata in the section. 
Fig. 13. Germination of basidiospore. 
Fig. 14. Basidia and paraphyses. Flemming fixation. The granules are evident 
in the basidia, but no filaments lie in the plane of focus. 
Fig. 15. Basidia. Formol-chrom-acetic fixation. Granules and one filament visible. 
Fig. 16. Two basidia in a hymenium, above which is seen the tissue of the parasitic 
Tremella. Notice the larger corpuscles in the basidia. 
Plate XXXIII 
(All figures X 880) 
Fig. 17. Filiform paraphysis. 
Fig. 18. Nodulose paraphysis. 
Fig. 19. Young basidium showing granules and filaments. 
Fig. 20. Basidium in lower part of hymenium, perhaps old but crowded for room 
and unable to elongate. No cross wall is here present. 
Fig. 21. Growing basidium showing cap of granules and one filament above the 
fusion nucleus. 
Fig. 22. Several filaments visible, one occupying an exceptional horizontal position. 
Fig. 23. Aggregation of granules apparently proceeding to apex of basidium. Fila- 
ments tending toward the growing sterigmata. 
Fig. 24. Sterigma broken loose from the basidium in the course of preparation, the 
filament remaining intact. 
Fig. 25. Beaked daughter nuclei ready to proceed into sterigmata. No fibrils are 
seen attached to them. 
Fig. 26. Degenerating basidium from hymenium parasitized by Tremella sp. The 
large corpuscles stain with Sudan III. 
Fig. 27, Old vacuolate basidium after sporulation. 
Fig. 28. Spores in process of formation. The one at the left shows a filament and 
what is probably a nuclear spindle. 
