lOO 



BOTANICAL GAZETTE [august 



20. Plowright, C. B., a monograph of the British Uredineae and Ustilagineae 



20. London: Kegan Paul, Trench & Co. 1889. 



21. PoiRAULT, G., and Raciborski, M., Sur les noyaux des Uredinees. Jour. 



de Botanique 9:318. 1895. 



22. Richards, H. M.,' On some points in the development of the aecidia. Proc. 



Amer. Acad, 31:255-270. 1896, 



23. Rosen, F., Studien uber die Kerne und die Membranbildung bei Myxo- 



myceten und Pilzen. Cohn's Beitrage 6:237-266. ph. 2, j. 1892. 



24. RozE, E., UUredo chrysanthemi parasite du Chrysanthemum indicum. 



Bull. Soc. Mycol. France 17:76. 1901. 



25. SAPPiN-TROUFfY, P., Recherches histologiques sur la famille des Uredinees, 



Le Botaniste 5:59-244. 1896. 



26. ScHtJRHOFF, P., Das Verhalten des Kernes im Wundgewebe. Beih. Bot. 



Centralbl. 19:359. 1906. 



27. Winter, G., Die Pilze. Rabenhorst's Kryptogamen -Flora I. 1:226. 1884. 



EXPLANATION OF PLATE VII 



Figs, i-ij were drawn with the camera lucida, using ocular IV and the 

 -^l oil immersion objective of Leitz. Figs. 18-22 are semi-diagrammatic and 

 the magnification has been adjusted to bring the figures of the different rusts 

 to approximately the same dimensions on the plate. 



Phragmidium potentillae canadensis 



Fig. I. — A portion of the mycelium showing the binucleated condition of 

 the cells of the secondary uredo. 



Fig. 2. — The first spore-initial cell dividing into spore and stalk cell. 

 Fig. 3. — An early stage in the budding-off of the second spore. 

 Fig. 4. — A fully formed second spore-initia 



Fig. 5. 



spore and stalk have been 



pleted; the stalk of the first spore is also sho"v\Ti. 



Fig. 6.— a portion 



h 



Puccinia podophylli 



Fig. 7. — A stage st 

 Fig. 8. — The spore 



teleutospo 



Fig. 9. — Sin 



cell with nuclei. 



teleutospo re (see jig 



spore 



Fig. 10. — A* second spore-initial cell showing nuclear division before division 

 into stalk and spore. 



Fig. t2. — A sta^^e showing the division of the distal cell into the two cells 

 the spore. 



