36
Scientific Memoirs by
With chlor. zinc. iod., the upper riper spores become greenish brown, whilst
the younger spores and basidia assume a pale-sherry colour. As many as 24
spores may be counted in a detached row. They have no intercalary cells. The
spores are very pale yellowish-white by reflected light, and when dry are usually
faceted. In water and by transmitted light, they appear as yellow round bodies
with finely granular contents. Externally they are beset with very deciduous tuber-
cles (Fig. 6, Plate IV, and Fig. 8, Plate V). The moistened spores measured on an
average 15. 6 X 13. 1 µ and t hese measurement s were very uni forml y mai nt ai ned.
In germinating, the æcidiospores throw out curved germinal tubes, which contain
pale yellow oil globules as well as clear watery parts and granular protoplasm.
The tubes measured 4 µ in diameter. Frequently these æcidiospores refused to
germinate, and then after lying a few days in water, the spores generally lost much
of their colour, and their contents were resolved into a number of round colourless
globules mostly double-contoured and of various sizes (Fig. 7, Plate IV).
Uredospores. —The uredospores are elliptical or pyriform bodies borne singly
on stalks shorter than their long diameters. They measure from 19.8 x 13.5 µ to
19.2 x 12.8, and are beset externally with prominent tubercles (Fig. 10, Plate V).
They are pale yellow by transmitted light, with a thick epispore beset with pro-
minent tubercles. At the equator of the spore two germinal pores may be seen
after it has lain for some hours in water. Among the uredospores some club-
shaped paraphyses always occur. Placed in water these uredospores germinate
readily, throwing out one long germinal tube which is unbranched, or with one or
two very short lateral protuberances. No germinal tube issues from the other
germinal pore. The germinal tubes measure 4 to 5 µ in diameter.
Teleutospores. —The teleutospores are two-celled bodies, and therefore belong
to the class of Puccinia. They are dark brown and given off singly on long stalks
of about 56 µ in length and 5 µ in diameter. The spores are very firmly adherent
to their beds. Each compartment of the spore is generally considerably longer
than it is broad, but occasionally spores may be seen in which the two com-
partments are nearly spherical. The upper compartment is usually much
deeper in colour than the lower and more, spheroidal. The lower cell usually
tails off, contracting gradually towards the stalk, which is broadest where it joins
the cell, narrowing gradually lower down. Hence the lower cell appears gradu-
ally to contract to the narrow diameter of the stalk (Fig. 11, Plate V). An
abnormal form in which two spores are borne on a single stalk is not uncommon
(Fig. 17, Plate V). The free end of the spore is generally thickened to the extent
of about 6 µ and conical, and a clear vesicular space may generally be seen in each
compartment. The length of the upper compartment varies from 24 to 20 µ,
and its breadth from 12 to 17 µ, whilst the length of the lower cell varies from
20 to 14 µ, and its breadth from 12 t o 14 µ. Among t he t el eut os por es s cr aped
off their beds a few uredospores may always be found, from which it may be
concluded that the same mycelium produces both forms of spores. When