Dastur . — Cytology of Tilletia Tritici, ( Bjerk .) Wint. 403 
primary sporidium by its falcate shape and size ; it is shorter and broader 
than the primary sporidium. In the majority of cases observed the 
secondary sporidium has been found to be uninucleate (PI. XX, Figs. 18, 
24-7, 33, and 38). Dangeard, Rawitscher, and Paravicini have always 
found the secondary sporidium to be binucleate. Paravicini, 1 however, states 
that since the two nuclei in the ‘ Sichelkonidien ’ (i. e. the secondary conidia) 
are situated equatorially, they can be distinguished only with difficulty. 
It is probable that he may have really seen the uninucleate ‘ Sichelkonidien \ 
There seems to be no doubt that the majority of secondary conidia 
observed in the present investigations are really uninucleate. This point 
has been confirmed many a time by the use of Heidenhain’s haematoxylin, 
Breinl stain, and gentian violet-orange G combination. This point has 
also been confirmed in the case of Tilletia on wheat collected by my friend 
Mr. W. L. Waterhouse from Pembroke, Wales, in February. Where and 
when the fusion between the two nuclei of the conjugated sporidia takes 
place it is difficult to decide. However, a few distinct cases of the fusion 
in the secondary sporidium have been found (PI. XX, Fig. 30). The 
secondary sporidium may bud off a tertiary sporidium (PL XX, Fig. 19), or, 
what is more commonly the case, it puts forth a germ-tube which may 
develop a tertiary sporidium (PI. XX, Figs. 32, 34, and 37). The tertiary 
sporidium is usually smaller than the secondary sporidium, and always 
uninucleate. The secondary sporidium may become septate on germination, 
like the primary sporidium (PI. XX, Figs. 34 and 37). 
The secondary sporidia, in some cases, show definitely two nuclei 
(PI. XX, Figs. 22, 28, 29, 30, and 34). At times the two nuclei are so close 
together as to arouse the suspicion that the pair is in the process of fusion 
(PI. XX, Fig. 23). The nucleus of the secondary sporidium passes as 
a whole into the germ-tube and the tertiary sporidium (PI. XX, Figs. 32 and 
33), or it divides either before or after the germination of the sporidium 
(PL XX, Figs. 21, 35, and 36). In a few cases the division has been found 
to have begun while the secondary sporidium is still attached to the germ- 
tube of the primary conjugated sporidium (PL XX, Fig. 21). One of the 
daughter nuclei passes into the germ-tube or the tertiary sporidium and the 
other remains in the sporidium (PL XX, Fig. 19), possibly to provide for 
further germ-tube or sporidial formation. This division may give rise, at 
times, to a temporary binucleate condition, either on account of the early 
division of the nucleus before the secondary sporidium has germinated or 
delayed migration of one of the daughter nuclei into the germ-tube. And 
therefore it is difficult, if not impossible, to determine the pedigree of the 
two nuclei found in the sporidium — whether they are the original two 
conjugate nuclei or whether they are the daughter nuclei of the single 
nucleus which has resulted from the fusion of the two conjugate nuclei. 
1 Paravicini, E. : loc. eit., p. 76. 
