125 
Barberries in my garden is clear from the fact that there were no Aicidium-spores 
there until many days later. 
TuirpD Stace: CLUsTER-cups—A®cIpIum (FIG. 3). 
The Meidium berberidis, which, under any circumstances, must be regarded 
as the result of the promycelium spores of Puecinia graminis, is a far more attrac- 
tive fungus, from an esthetic point of view, than either of the preceding forms ; 
when seen by a low magnifying power, it is seen to consist of a beautiful cluster 
of minute cups filled with golden-yellow spores. These cups are formed of a mem- 
brane which forms a circle of whitish teeth round their mouths. They are always 
in groups and are cylindrical in form. The spores which fill them are subglobose, 
smooth, golden-yellow, and measure from 15 to 25 mk. in diameter. They, like 
the Uredo-spores, are developed from mycelium, but in quite a different manner; 
for, instead of being produced singly, they are formed in chains, one above 
another, from the bottom of the cup, the oldest and ripest spore being at the top. 
This, when mature, falls off, to be succeeded in the course of a few hours by the 
one next below it. Ifa leaf with the dZeidiwm upon it be put upon a glass slide, 
it, in the course of a few days, will deposit a mass of yellow dust. If a small 
quantity of this powder, which, of course, consists of spores that have been shed 
by the -Zeidiwm, be placed on a drop of water, few, if any, of the spores will ger- 
minate, for the reason that they are immature and have fallen out of the cup 
because the plant has lost some of its moisture by evaporation. It is important to 
bear this in mind, as it is often the cause of failure in experimenting with the 
Uredines. The ripe Aicidium-spore germinates in the same manner as the Uredo- 
spore does. The germ-tube is protruded through one of the six openings which 
exist, at any rate potentially, in the epispore. The yellow endochrome is passed 
in the same way to the end of the convoluting branched germ-tube which is 
destined to enter the stomata of a graminaceous plant. If, however, the Aucidium- 
spores fall—as they, of course, constantly do—upon the Barberry leaves, they do 
not reproduce the eidium berberidis, for if their germination be watched upon 
the cuticle, it will be found that their gerin-tubes do not enter the leaves. Hence 
they differ very considerably from the Uredo-spores, which, it will be remembered 
continuously reproduced themselves upon their host-plant. Neither will the germ- 
tubes of the Uredo-spores, if the latter be sown upon barberry leaves, enter them, 
Nor is the ecidiwm ever produced from the Uredo-spores. 
FourtH Form: SPERMOGONIA (FIG. 4). 
Besides the Cluster-cups, there exists in company with the Zeidium, another 
important set of reproductive organs which are developed from the same mycelium 
and to which the name of Spermogonia has been applied. Spermogonia can be seen 
as minute dark specks upon the opposite side of the leaf, and immediately over 
the place occupied by the Zeidium. In point of time, they are the first organs 
produced by the mycelium of the promycelium spore, and they last as long as the 
Aicidium does. Sometimes they are produced alone, and are not accompanied by 
the #cidiwm,* but this is an exceptional although not unique occurrence. Each 
oo  — 
* Cooke, Microscopic Fungi, edit. 4, 1878, p. 29. 
