270 PROCEEDINGS OP THE AMERICAN ACADEMY. 



EXPLANATION OF PLATE. 



^cidium of Uromyces Caladii on Pellandra. 



1. Section of primordiiini showing fertile hyplia. X 320. 



2. Older stage, where the fertile hypha has begun to bud. X 320. 



3. Young stage of a large iecidium sliowing several points of origin of hyme- 



niuni. The peridium has begun to form. X 320. a. Showing the 

 formation of the peridium at a somewhat later stage. X 320. 



4. More advanced stage of same. The pseudo-parencliyma has ruptured. 



X 320. 



5. a. Single ripe spore showing double nucleus, b. Spore vvitli tliree nuclei. 



X 1250. 



6. Young spore just cut off from the basidium showing nuclei, h. Spore; 



older, but not yet mature. X 1250. 



jEcidium on Iloustonia arrulea. 



7. Section of primordium with fertile hypha. X 320. 



8. Older stage, showing connection of fertile hypiia with young basidia. Not 



quite median although showing the fertile hypha. X 320. 



9. Section of young aecidium, showing a soniewliat older hymenium. X 320. 



^'Ecidium on Raiiunctdus. 



10. Section of primordium with fertile hypha already budding. X 820. 



11. Section of an almost mature aacidium, in which the connection of the fertile 



hypha with some of the basidia is plainly shown. X 320. 



12. Young basidia from ascidium on Anemone (yEcidhim punctalum). Tlie 



sterile hyphse, the contents of which are not so granular, show among 

 the fertile ones. X 560. 



13. Margin of a section of aecidium on Sambucus, showing origin of the 



peridium. X 560. 



14. Young fficidium of Peridermium elatinum. X 320. 



All the drawings were made with the aid of an Abbe' camera and reduced 

 about one third in reproducing Figures 3, 3rt, 4, 5, 6, 7, 9, and 14 were drawn 

 from microtome sections, the rest from hand sections. All were treated with 

 lactic acid, and stained before drawing. 



