6o 
C. A. LUDWIG AND C. C. REES 
EXPLANATION OF PLATE VIII 
All drawings were made with the camera lucida, and all illustrations are from 
stained microtome sections except No. 4, which was made from spores scraped from a 
dry herbarium specimen and mounted in water. 
Fig. I. Young sorus oi Pucciniastrum A grimoniae. X 1360. 
Fig. 2. Vertical section of ostiole of mature sorus. X 1360. 
Fig. 3. Mature sorus of Pucciniastrum Agrimoniae. X 290. 
Fig. 4. Outline sketch of urediniospores. The hilum is indicated at the 
bottom of the spore in each case. X 825. 
