Das fair. — Cytology of Tilletia Tritici , ( Bjerk .) Wint, 407 
The presence of the two nuclei in the secondary sporidium is, at least 
in some cases, due to the division of a single non-conjugate nucleus. 
The secondary sporidia germinate and may develop tertiary sporidia 
which are uninucleate. 
The hyphae, at least in the early stages of the infection of wheat 
seedlings, are uninucleate or multinucleate. 
Botanical Laboratory of the Imperial College 
of Science and Technology. 
September , 1920. 
EXPLANATION OF PLATE XX. 
Illustrating Mr. Jehangir Fardunji Dastur’s paper on the Cytology of Tilletia Tritici , (Bjerk.) Wint. 
* • _ ; j dr 
Fig. 1. A germinated spore; the promycelium bears nine sporidia; it has only two nuclei. 
X 1,300. 
Figs. 2-5. Germinating spores. In Fig. 2 the promycelium has a dividing nucleus. In Fig. 3 
the lower of the two nuclei in the promycelium is dividing. In Fig. 5 the lowermost nucleus in the 
promyceljum is dividing. Figs. 2 and 3, x 1,450. Figs. 4 and 5, x 1,300. 
Figs. 6 and 7. Early stages in the development of the sporidia. Fig. 6, x 1,100. Fig. 7, 
X 1,300. 
Figs. 8 and 9. Sporidia fully developed'; the nuclei are still in the promycelium. In Fig. 9 two 
nuclei are seen migrating towards the sporidia. x 1,300. 
Fig. 10. Sporidia on a lateral branch, x 1,750. 
Figs. 11 and 12. Branched promycelia with several nuclei, some of which are seen dividing in 
Fig. 11. Fig. 11, x 1,300. Fig. 12, x 1,100. 
Figs. 13 and 14. Conjugating sporidia. x 1,300. 
Figs. 15 and 16. Uninucleate sporidia. x 1,450. 
Fig. 17. A binucleate sporidium. x 1,300. 
Figs. 18-38. Secondary sporidia, some of which are germinating. In Fig. 21 the secondary 
sporidium is seen attached to a short germ-tube, which has developed from a conjugated sporidium. 
The nucleus is dividing. In Fig. 18 the nuclei are fusing. In Figs. 23 and 24 the nuclei are 
dividing. Figs. 18-21, 23, 24, and 26, x 1,450. Figs. 22 and 25, x 1,300. 
Fig- 39* A group 01 three sporidia. x 1,300. 
