328 Blackman. — On the Fertilization , Alternation of 
a sheath round the two middle cells, but exists also round the upper part of 
the top cell and the base of the lowest cell (Fig. 2). The stalk has a narrow 
lumen which widens out below (Figs. 5 and 86 e) ; its wall shows only- 
slight differentiation of layers. Each cell has usually four pores which are 
closed on the outside by the cuticle only, the protoplasm and endosporium 
projecting slightly into the cavity in the mesosporium and exosporium 
(Fig. 2). Each cell contains a single central nucleus with a well-marked 
nucleolus, and dense cytoplasm containing a quantity of yellow oily 
material which gives to it an orange colour. In the dry state very little can 
be made of the structure of the nucleus, and except for the nucleolus it 
appears almost homogeneous. 
Germination . Spores taken in March from the ‘ wintered ’ leaves 
germinate readily in moist air or water, but will not do so earlier. The first 
beginning of the germ-tube (promycelium) is the welling out through one of 
the pores of a spherical mass of yellow cytoplasm surrounded, of course, 
with a thin wall. This stage (Fig. 1) is very striking, and is also to be 
observed in G. clavariaeforme. From this spherical mass the cylindrical 
germ-tube grows out away from the spore (Fig. 5). 
The nuclei undergo an interesting series of changes when the spores 
have been lying in water some time. After twelve hours in this condition 
the nucleus increases in size, and there is to be observed a somewhat 
flattened nucleolus pressed close against the nuclear membrane, which often 
projects at this point. The faintly staining, and hitherto almost homo- 
geneous, mass of the nucleus begins to stain more darkly, and faint 
indications of a chromatin thread are to be seen (Fig. 3). Soon the 
chromatin part becomes clear as a single much-twisted thread, at first 
closely coiled ; but as increase in size of the nucleus still goes on the 
coil becomes a more open and thinner spireme thread. This stage, how- 
ever, is not a preparation for division, for it appears to last only a short 
time, and very soon the nuclei return to the ordinary condition and show 
a nucleus with a chromatin network, and, instead of a single large nucleolus, 
a few smaller ones (Fig. 4). The nucleus has a large cavity and is only 
partly filled with the network, so that in the living teleutospore examined 
in water before germination it appears as a distinct, clear { vacuole 5 (Fig. 5), 
as it was termed by the older observers. 
In some few cases two smaller nuclei are to be found in the cell of the 
teleutospore (Fig. 4 a) instead of one larger one. These are, no doubt, the 
original paired nuclei of the teleutospore, which for some reason have 
delayed their fusion. Their fate is unknown, as two nuclei were never 
observed to pass into the germ-tube ; probably they fuse later. There was 
no evidence that they represented the results of a precocious division. 
The nucleus passes into the germ-tube, being constricted in its passage 
through the pore, which is only of small diameter (Fig. 6). If the germ-tube 
