88 Cayley. — Some Observations on the Life-history of 
of large multinucleate cells (Fig. 5). Portions of the ascogonia appear to 
be narrower and stain more deeply than others, but whether these portions 
are of the nature of trichogynes, or whether they are the portions which are 
growing the most actively, could not be determined. No nuclear fusions 
were observed in the ascogonia, but the nuclei tend to associate in pairs as 
the ascogonial cells mature (Fig. 5). In one instance only (Fig. 22) there 
were indications of the passage of the nucleus of one cell to another. As 
will be seen in the figure, there is a large and very definite nucleus in one 
cell and a definite pore in the cell-wall, through which a nucleus of a 
neighbouring cell is about to pass. It will also be seen that some ascogonial 
cells are in a more advanced stage of disintegration than others. The 
culture from which this preparation was made was grown on potato- 
glycerine from ascospores obtained from dehiscing perithecia on bark, and 
was thirteen weeks old. Figs. 19, 20, 21, 22, are consecutive sections of 
the same perithecium cut 3 /ot thick. 
The ascogonia do not appear to function, in that they do not give rise 
directly to ascogenous hyphae. Two or more ascogonial nuclei pass into 
the hyphae which grow out from the ascogonial cells. The ascogonia 
gradually degenerate and the hyphae in their turn completely fill the cavity 
of the perithecium. The actual ascogenous hyphae which give rise to asci 
arise de novo at the base of the perithecium, from cells which contain two 
or more nuclei showing the same characteristics as the nuclei of the 
ascogonia, namely, they have a well-marked nucleolus and nuclear area, 
and occasionally show chromatin granules. The origin of these basal cells 
could not be traced. The nuclei of these cells are of two sizes, large and 
small, as seen in Fig. 18, but it was not possible to determine whether the 
larger were the result of the fusion of two smaller nuclei. The smaller 
nuclei tend to associate in pairs at this stage also. The perithecium is 
completely filled with paraphyses before the asci begin to develop. In 
spite of careful search, no crosier formation or further nuclear fusions could 
be found prior to the development of the ascus, and the study of the nuclear 
divisions in the ascus had to be abandoned owing to difficulties in technique. 
All fixatives so far used for the purpose of fixing perithecia at the stage 
at which the asci develop either failed to penetrate the hard outer 
perithecial wall, or, if the penetration was satisfactory, microtome sections 
could not be cut sufficiently thin. The large number of paraphyses present 
and the extreme smallness of the whole structure made accurate observations 
impossible. 
The ovoid perithecia contain numerdus asci, which can be seen in all 
stages of development in the perithecium. The asci contain eight two-celled 
ascospores with thick, slightly roughened walls (Figs. 9, 14). The ascospores 
emerge as yellowish-white tendrils through the raised ostiolum at the apex 
of the perithecium. On the host plant perithecia begin to form in the late 
