EXPLANATION OF PLATE. 



1 to 5. Germinating uredospores of Cronartium asclepiadeum, Fr. ; x 330, except Fig. 3, 

 which = x 370. 



6 and 7. Base of the ligules accompanying the uredospores. 



8. Transverse section through a ligule, showing the same to be solid, not tubular. 



9. A ligule in process of germination. 



10, 11, and 12, show more precisely the manner of producing the promycelial spores. 



13. Promycelial spores germinating. 



14. The uredo sorus of Cronartium asclepiadeum, showing the uredospores escaping through 



an aperture in the peridium. 



15. Section through a more advanced uredo sorus after the appearance of the ligule ; the 



peridium is thrown back, and shows the manner of growth of the uredospores ; x 230. 



16. Section of the same, taken longitudinally through the axis of the ligule. 



