XXII 
INTRODUCTION. 
Sori pustular, pale 3. 
Spores agglomerated. 
Enclosed in a common tegument . . 5. 
Adherent without tegument. 
All fertile ........ 6. 
Peripheral sterile 8. 
Soon becoming free 7. 
Spores seated on a definite stroma . 10. 
Spores enclosed in a peridium ... 9. 
Entyloma. 
Doassania. 
Thecaphora. 
Urocystis. 
Sorosporium. 
Cerebella. 
Qraphiola, 
A similar course may also be adopted with the Uredines, 
bearing in mind that in this group the spores are not virtually 
all unicellular, as in the foregoing. No account need betaken 
here of the complications of development. 
UJtKDINE;E. 
Telentospores continuous, one-celled . Amerospoiue. 
Sori horizontal. 
Pulverulent 11. Uromyces. 
Forming a crust ....... 12. Melampsora. 
Sori vertical, forming a columella . 13. Cronartium. 
Telentospores bilocular Didvmospou.k. 
Sori horizontal 14. Puccinia. 
Teleutospores 3, or many-septate . . Phragmospora;. 
Uredospores solitary. 
Teleutospores cylindrical. 
Pedicels free 15. Phragmidium. 
Pedicels adglutinate .... 16. Uamaspora. 
Uredospores catenulate. 
Telentospores with a thick coat . . Coleosporium. ' 
Telentospores transversely and longi- 
tudinally septate Dictyospo r.v:. 
IMPERFECT UREDINES. 
Psendoperidium present. 
Cup-shaped . 17. JKcidium. 
Elongated 18. Rastelia. 
Pseudoperidium absent. 
Uredospores unicellular, solitary on 
deciduous pedicels 19. Uredo. 
The story of the Uredines is hardly to be told within the limits 
of this introduction, although it is one which has a consider- 
able interest for the agriculturist. We do not pledge ourselves 
to any theory of heteroecism, inasmuch as we fail to recognize 
it as satisfactorily proven, but we would not ignore the 
existence of snch a theory, and that it has many followers. To 
illustrate the phases of these parasites we may accept some 
species of Puccinia as a type. In the first instance the host- 
plant produces upon its loaves, in the spring, clusters of little 
cups, partly imbedded in the substance of the leaf, which is 
usually thickened and discoloured. These little cups constitute 
the A'J cidium-f ovm , the margin is usually white and fringed, 
and the interior filled with orange subglohose spores, produced 
in chains, hut soon falling apart. The ascidiospores will 
germinate when mature, and produce a thread of mycelium. 
Smaller bodies are also to he found in company or in proximity, 
