M e d i c a l O f f i c e r s o f t h e A r m y o f I n d i a .
29
beneath show a deep central depression corresponding with the bases of the
spore-cells (Fig. 6, Plate I). Immediately around this an imperfect cuticular
ridge is present, indicating the site where the outer surfaces of the peripheral
basal cells were attached to the outer edges of the bases of the corresponding
spore-cells (Fig. 5, Plate I). External to this is the zone corresponding with
the extero-inferior surfaces of the peripheral spore-cells, surrounded externally by
the line of tubercles separating these surfaces from the true apical areas of the
same cells.
The size of individual spores varies very greatly, due to the varying number
of stems and basal cells from which they originate. Those of average size and
regular form measure about .085 mm. in diameter and about .023 in height,
but in, some cases they may attain a diameter of .1 mm. and a height of
.04 mm. Others again are very small. The size is determined by the number
of spore-cells present, the latter varying very little in magnitude, as a rule. The
central cells at their upper extremities present hexagonal, pentagonal, and rarely
quadrangular faces. The marginal ones are pentagonal or quadrangular, and are
somewhat larger, or at all events broader, than the central ones, giving diame
-ters of about 19.8µ X 16.5µ to the surface of the thick epispore, which is here
about 3µ in thickness, while the central cells are about 16.5 x 14.8µ. Some
spores contain as few as seven cells, and others as many as thirty-seven or more.
Each mature cell contains a finely granular protoplasm, including a clear nu
-clear area and in many cases one or more oil globules.
All attempts at artificial cultivation of teleutospores have as yet failed to
give any results. The uredospores, on the other hand, germinate freely in infusion
of the leaves of the host. Several attempts at artificial infection by means of
teleutospores have been made, but only in one case was there any apparent re
-sult. This, however, may have been due to the fact that the seedling plants
which were supplied for experiment as specimens of Albizzia Lebbek eventually
turned out not to belong to that species, but to Albizzia procera. In the case in
which a result appeared the pinnules of a healthy seedling were smeared with
water containing an abundance of teleutospores, and shortly afterwards showed
two patches of spermogonia, agreeing precisely in character with those nor
-mally developed on Albizzia Lebbek.
Late in the season, and shortly before the fall of the leaves, a second and
very distinct form of teleutospore often occurs in the persistent uredosporic
pustules on the under-surfaces of the pinnules (Fig. 1, Plate II). They arise
by simple stems about .059 mm. in length from the same bed of small-celled
tissue as the surrounding uredospores of the pustule. The spore is rounded
and apparently composed of four cells, surrounded by a common thick epispore,
of dark sepia colour, and beset with a number of peculiar olive-green processes,
about 10µ. in length, arising by dilated bases and terminating above in stellate
expansions (Fig. 4, Plate I). The body of the spore without the processe