„8 DIVISION I.--GENERAL MORPHOLOGY. 
transverse zone lying in the middle of the ascus, or in most other species into a mass 
which fills the upper third or fourth portion of the ascus; the remaining and especially 
the lowermost portion contains only the glycogen-mass which is marked by many 
vacuoles of varying size and arrangement. Sometimes, as in Morchella esculenta 
and Peziza Acetabulum, the uppermost portion of the ascus above the protoplasm is 
occupied by a layer of glycogen, the protoplasm filling a cavity with a sharply 
defined outline in the glycogen-mass. The nucleus always lies in the protoplasm and 
in or near its centre, at which point the spores are formed in these as in other species, 
the mode of formation being essentially the same as that described above. The young 
spore-primordia are in contact with one another in Peziza convexula and Morchella 
esculenta. Only the first stage in the division and the ultimate eight nuclei, round 
which the formation of spores takes place at once, have been directly observed in 
most of the above species; the other stages have been seen only in Peziza convexula. 
But the accounts which we possess and observations on the formation and division 
of nuclei in other plants compel us to assume, that the process in the eight-spored 
ascus are essentially the same in all cases and that the successive stages in the division 
of the nucleus have simply been overlooked, owing partly to the rapidity with which 
the operation is effected and partly to difficulties of observation of other kinds. 
Numerous independent observations on a considerable number of Discomycetes with 
eight spores formed simultaneously in one ascus have established the presence of 
the primary nucleus before the formation of spores, the appearance of the young 
spores in the manner just described, and the occurrence or non-occurrence of differen- 
tiation of the glycogen-mass and protoplasm according to the species. There is therefore 
no reason to doubt, that the course of development above described prevails very 
generally in the group which contains the genera Peziza, Phacidium, Leotia, Ascobolus 
and Geoglossum. It is often difficult to follow it throughout in large asci, like 
those of Leotia lubrica, Geoglossum hirsutum, Helvella, &c., because the protoplasm 
of the young tube and of the spores is rendered opaque by the number of drops of 
oil. In very many other cases the minuteness of the asci and spores either prevents 
a complete observation or renders it difficult ; but even in these cases a little attention 
will enable us to see the primary nucleus, the simultaneous appearance of the eight 
spores as portions of protoplasm with a fine boundary-line, and sometimes (Sclerotinia 
sp.) a nucleus in each of them. Inthe small asci of e.g. Peziza tuberosa, P. Sclerotiorum, 
P. calycina and Phacidium Pinastri, and also in some larger ones, as those of Lecidella 
enteroleuca, Pertusaria lejoplaca, Lecanora pallida and Sphaerophoron coralloides, 
the primary nucleus appears as a strongly refringent roundish body, which is either 
homogeneous or more pellucid and as if hollowed out in the centre; the clear, trans- 
parent, spherical space is not or not always (Peziza Fuckeliana) to be seen through the 
periphery. 
It is more difficult to observe the formation of the spores in the asci of the Pyreno- 
mycetes containing eight spores formed simultaneously, than in the Discomycetes, 
on account partly of the minuteness and delicacy of the organs, partly of the presence 
of oil globules which are present usually in large numbers in the protoplasm. Yet 
careful observation shows that the spores are formed in the way described above. 
A nucleus has rarely been seen in them (Sordaria fimiseda, Fig. 52). An oil globule 
was often taken for a nucleus by older writers. The primary nucleus on the contrary 
may be distinctly seen in many species before the spores are formed; it has the 
characteristics of the nucleus of Peziza calycina and P. tuberosa which have just been 
described, and always lies in the same position a little above the middle of the ascus, 
for example in the nuclei of Xylaria polymorpha, Nectria, Sphaeria obducens, 
Curcurbitaria Laburni, Pleospora herbarum, Sordaria fimiseda, De Not., and some 
