992 The American Naturalist. [December, 
uredospores secondary or accessory conidia (stylospores) In - 
many cases the ascus-wall is readily separable from the con- 
tained spore or spores; but for the most part, the ascus-wall 
is so closely adherent as not to be distinguished from the 
spore-wall without treatment by potassic hydrate or other 
reagents. 
In one genus, Uropyzis, the ascus is much larger than the 
double spore it contains, and may be observed very easily 
without special preparation. (Fig. VIII of Plate XXXII.) 
In Gymnosporangium in fresh material an ascus cavity con- 
siderably larger than the double spore can be seen in carefully 
made preparations. Young *teleutospores " of Phragmidium, 
in which the spores have not yet attained full size, show the 
ascus-wall very clearly, (Fig. IX of Plate XXXII), although 
in mature specimens by the enlargement of the spores it can be 
seen with difficulty, if at all. By careful examination, one may 
make out the ascus-wall in a good many cases where other- 
wise it might be overlooked. I have little difficulty in dis- 
tinguishing it in some species of Uromyces (where the ascus 
contains but one spore) and Puccinia (where the ascus con- 
tains one double spore, or more accurately speaking, two 
spores), especially after the application of strong potassic 
hydrate. 
THE QUESTION OF RELATIONSHIP. 
The view here set forth, that the so-called “ teleutospore " is 
an aseus with its contained spore or spores, involves the sup- 
position that the Uredineae have suffered much structural de- 
generation. When we consider the fact that they are, as we 
may say, intensely parasitic, there is no improbability that we 
are dealing here with a greatly reduced plant structure. One 
has but to contrast a Dodder with a Morning Glory, or a 
Broom-Rape (Aphyllon) with a Figwort (Scrophulariaceae) in 
order to realize what great changes are produced by a para- 
sitic habit. It has long been well known in biology that the 
greater the parasitism of an organism the greater is its degen- 
eration. Some plants take but little from their hosts, and still 
maintain their roots, stems and leaves with so little change 
