Plate XIII.

1. Portion of leaf (half natural size) with disease spots. These are at first pale, afterwards becoming orange-coloured, and covered on the under surface with a bright yellow, then orange-coloured dust. The dark spot in the centre is due to the presence of another but unimportant fungus, a black Aspergillus.

2. Portion of cuticle of under surface of leaf viewed from outside, showing stomata and clusters of sporangia (which contain the spores), the aggregate of which forms the dust above mentioned × 150.

3. Portion of cuticle of under surface of leaf viewed from inside, showing mycelial filaments connected with dark bodies, which exteriorly bear the sporangia × 150.

4. Dark body extricated from the leaf; it bears a cluster of sporangia above, and has the mycelical filaments attached to it below × 200.

5. 6, 7. Mycelium from the interior of a "diseased" coffee leaf × 350.

8, 9. Clusters of sporangia, from which the ripe individuals have been separated by washing × 400.

10, 11, 12. Figures showing structures (possibly some parasitic organism) found on sporangia clusters from Sumatra × 250.