404 Dastur . — Cytology of Tilletia Tritici, (Bjerki) Wint. 
The nuclear condition of the hyphae in the very early stages of 
infection of wheat seedlings from two to eight days old has also been 
studied. Seedlings a day old were inoculated with cultures from germinated 
spores, and then were incubated at 50° C., and fixed in Flemming’s weak 
solution from time to time. 
The infecting hypha, as a rule, enters the first or outermost leaf- 
sheath between the epidermal cells. It makes its way in by pushing aside 
the adjoining walls of these cells (Text-figs. 1-7), and at times the walls are 
consequently ruptured (Text-fig. 7). Direct entry of the germ-tube in the 
lumen of the epidermal cells takes place very rarely (Text-fig. 8). 
The infecting hypha and the hyphae of the later-formed mycelium are 
uninucleate or multinucleate (Text-figs. 1-9) ; in no case were the hyphae 
uniformly binucleate. In some cases two nuclei in close association were 
observed, but they may be the daughter nuclei of a recently divided nucleus, 
or the paired condition may be accidental and temporary. 
Schmitz, 1 in 1879, investigated Ustilago longissima , (Sow.) Tub, and 
found the hyphae from which the spores developed to be multinucleate. 
According to Fisch 2 the hyphae of Tilletia , Urocystis , and Ustilago are 
mostly multinucleate. Dangeard, 3 as the result of his researches in the 
cytology of several members (including Tilletia ) of Ustilagineae, states that 
the mycelium of this group is multinucleate. But Lutman, 4 disagreeing 
with these authors, says his observations show that ‘ this statement that the 
mycelium is made up of multinucleated cells is probably true of the genus 
Ustilago , but it is not true of the Tilletiaceae ’. He believes the Tilletiaceae 
to be binucleate ; and Maire, 5 6 Rawitscher, 0 and Paravicini 7 also agree that 
in Tilletia Tritici the hyphae are binucleate. 
The observations described in this paper, as far as they concern the 
nuclear condition of the hyphae in the early stages of infection, support the 
views of Fisch and Dangeard. 
Rawitscher and Paravicini agree that the binucleate stage in the life- 
cycle of Tilletia is the result of the conjugation of the primary sporidia, and 
that the binucleate condition continues up to the development of spores, in 
which the two nuclei fuse, with the consequence that the mature spore is 
uninucleate. Here it may be noted that there seems to be some doubt as 
to the correctness of Paravicini’s observations of the binucleate condition of 
the Tilletia mycelium in the host plant, because the mode of spore formation 
1 Schmitz, F. : Untersuchungen iiber die Zellkerne der Thallophyten. Verh. des naturhist. 
Vereins der preuss. Rheinlande u. Westfalens, 1879, p. 361. 
2 Fisch, C. : Ueber das Verhalten der Zellkerne in fusionirenden Pilzzellen. Bot. Centralbl. 
vol. xxiv, 1885, pp. 221-222. 
s Dangeard, P. A. : loc. cit., p. 269. 
4 Lutman, B. F. : Life-History and Cytology of the Smuts. Wise. Acad. Sc. Arts and Letters, 
vol. xvi, Pt. II, No. 4, 1910, p. 1219. 5 Maire, R. : loc. cit. 
6 Rawitscher, F. : loc. cit., p. 313. 1 Paravicini, E. : loc. cit., p. 77. 
