of sexual organs in Aecidium . 
5i 
EXPLANATION OF FIGURES IN PLATE IV, A. 
Illustrating Mr. G. Massee’s paper on the presence of sexual organs in Aecidium. 
Fig. 1. Young oogonium of Aecidium ranunculacearum. x 400 diam. 
Fig. 2. Oogonium and antheridium of same, x 400 diam. 
Fig. 3- Oogonium of same after fertilisation ; with hyphae growing from the 
hypha supporting the oogonium, x 400 diam. 
Fig. 4. Oogonium of same at a later stage of development, showing the 
prominences which form basidia and peridium respectively, x 400 diam. 
Fig. 5. Young plant of same before rupture of peridium: a, peridium ; b, 
aecidiospores ; c, basidia ; d, external covering of hyphae, some of which originate 
from the hypha supporting the oogonium, others from the original weft ac- 
companying the oogonium ; e, epidermis of leaf, as yet unbroken by the parasite ; 
f, cells forming mesophyll of leaf, x 400 diam. 
Fig. 6. Aecidiospores of same germinating, x 500. 
Fig. 7 - Aecidiospores of same, germinating after having been under water 
for several weeks, and afterwards placed in a damp atmosphere, x 500 diam. 
