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Scientific Memoirs by
the septa, and separate, and apparently represent, sporidia. Frequently only three
of the four cells formed thus separate, the fourth not maturing. These detach
-ed cells, or sporidia, have usually one or two vacuolated spaces, and measure from
14 x 8µ t o 18 x 11µ (Fi g. 15a , b , c ,
P l a t e I I ) . I h a v e n e v e r , h o w e v e r , s u c c e e d e d
in getting them to germinate, unless, indeed, Fig. 15 a, plate II, represents the
germination of a spore not yet detached; but, on the other hand, this may, and
I think probably does, represent an abortive attempt at the usual sporidial forma
- t i o n t h r o u g h a s t e r i g m a . O f t h e n u m e r o u s c u l t i v a t i o n s I e x a m i n e d c a r e f u l l y
this was the only case exhibiting such growth, all the rest developing exactly as
I have described and depicted. The absence of any observed germination of these
sporidia makes one serious gap in the life-history of this fungus. It may also
be urged that this peculiar sporidial development is due to the unsuitable
media (water and a decoction of Smilax leaves) in which I placed the teleuto
- s p o r e s . T h i s o f c o u r s e i s p o s s i b l e , b u t a g a i n s t t h i s v i e w I m a y n o t e t h a t i t ,
and one other teleutospore, to which I shall presently allude, are the only
ones of the many teleutospores I have observed germinating, which develope so,
and that they invariably develope so most readily, and without any sign of hesi
- t a t i o n . I n 2 4 h o u r s a c u l t i v a t i o n p r e s e n t s i n n u m e r a b l e s u c h s p o r i d i a . T h e s i n g l e
other case to which I have alluded, is a Uromyces on Solidago verga-aurea, Lin.,
which behaves in exactly the same way, and in which, moreover, the peculiarly
developed sporidia germinate readily in water. Figure 16, Plate II, represents
the teleutospore before germination; Figure 17 a, one which has commenced to
germinate, but in which the promycelium still remains undivided; and Figure
17 b, the cast-off terminal end of another promycelium, with four sporidia still
adherent to one another, formed just as those of the Smilax fungus are, in two of
which germ tubes are thrown out. I will not here encumber this paper with a
detailed description of this Uromyces, but merely mention those points in support
of the views I take, that this sporidial formation is a new type of normal
germination.
The uredospores are oval, or more usually pyriform, pale yellow bodies, beset
externally with very prominent spines (Fig. 12, Plate II), and so closely resemble
the aecidiospores as to make it difficult to distinguish the one from the other.
Figure 9, Plate II, represents some spores from leaves which were collected early
in October, and preserved in botanical drying paper. The spores were sketched
late in November after the leaves had been 24 hours in a moist chamber. These
may be compared with fig. 8, Plate II, representing aecidiospores drawn under
exactly similar conditions. Among the uredospores a few club-shaped para
-physes may always be seen. The spores are formed singly on short stalks about
the length of their own long diameter (Fig. 6, Plate I). The fresh spores, after
lying a few minutes in water, measure on an average 46.5 x 31.7µ. The epi
- s p o r e i s t h i c k e n e d a t t h e b r o a d f r e e e n d . T h e s e s p o r e s d o n o t g e r m i n a t e a t a l l
readily in water: only in one of many cultivations did a few germinate, throwing