INTRODUCTION. 
XX1U 
sometimes on the opposite surface of the leaf. These have the 
form of minute embedded cells, containing very small hyaline 
spore-like bodies, called spermatia, whilst the cells which con- 
J tain them are spermogonia. What their function may be is as 
yet only conjectural, but they are nearly always present, and 
j presumably not without a purpose. Later on in the summer, 
the same, or others, develop on either, or both surfaces, small 
I brownish pustules, at first covered by the cuticle, but at length 
the pustule splits irregularly, and exposes a powdery brownish 
dust-like mass of nearly globose spores, each spore borne at 
first at the apex of a short hyaline thread, these threads 
arising from a cushion-lilce base of mycelium. These powdery 
spores constitute the “rust" or uredospores, and with them ends 
the second stage of the fungus, but how they are evolved from 
the first stage, or how they produce the third stage, is a 
mystery still . Nevertheless, the third stage is held to be the com- 
plete or perfect stage, and the spores produced arc teleutospores. 
these teleutospores are more or less elongated, divided by a 
septum across the middle into two cells, and supported upon 
hyaline spoi’ophores, or spore-bearing threads. They are pro- 
duced in pustules similar to those of the uredospores, and often 
mixed with them. A few of the teleutospores will sometimes 
he observed growing within the pustules of the uredospores. 
When the teleutospores are mature they do not always germi- 
nate at once, but a period of rest supervenes, and perhaps they 
may not germinate until the following spring. Each cell of 
the teleutospore is capable of sending out a germ-tube, 
through a special pore, and as this germ-tube grows, the con- 
tents of the cell of the teleutospore pass into the germ-tube, 
and to the extreme end. Ultimately a septum crosses the tube 
and prevents retreat. One, two, or more buds or processes 
appear at the end of the germ tube, and in time are converted 
mto secondary spores, or promycelial spores, into which some of 
the old spore contents pass, and then these smaller bodies are 
eligible for the production of tubes of mycelium, prepared to 
find an entrance into tho leaf of some new host plant, and com- 
mence the cycle over again. Thus, then, we have, in order of 
succession, spermogonia, aecidiospores, uredospores, and teleuto- 
spores, the latter producing promycelial spores, as the most 
complete and perfect condition of a Fuccinia. 
But all these stages are not always to be found associated 
together. The chain is not always perfect. In some cases the 
-dSridium only is known, with or without spermogonia, or only 
the uredospores are known, and in either of these eases the 
tungi are regarded as imperfect, or imperfectly known Uredines. 
Besides those cases in which aecidiospores, uredospores, and 
teleutospores are produced on the same species of host plant, 
there is another group, which those who have implicit faith in 
heteroecism contend, produce the fecidiospores, with their sper- 
mogonia on one plant, let us say a Berberry, and the uredo- 
