CHAPTER IIIL-—SPORES OF FUNGI.—GERMINATION. 113 
becomes invested with a very delicate membrane of its own and appears as a small 
vesicle which elongates in the outward direction as the germ-tube and grows 
through the episporium. In the thick-walled spores of Pertusaria the tubes often 
ramify inside the episporium and the ramifications spread in it parallel with the surface 
of the spore. The canals in the membrane are, as far as can be ascertained, new 
formations at the time of germination, and are not enlargements of primordial forma- 
tions. They continue usually so narrow that vesicles and germ-tubes appear at first 
sight to be completely surrounded. On acccunt of the slight thickness of the epi- 
sporium in Ochrolechia these project at an early period above the surface of the spore, 
and, as Tulasne observes, may often be separated with the episporium from the 
apparently uninjured endosporium. The use of reagents, especially Schulze’s solution, 
shows the state of the case to be everywhere as it has been described, and this is 
apparent in the large spores of Pertusaria even without their use (see the explanation 
of Figs. 57 and 59 A, &). 
In all cases the spore absorbs 
water before the commencement of 
germination, and as a consequence 
of this it swells and forms vacuoles 
(Fig. 58). If it contains a reserve 
of food in the form of drops of oil, 
these are seen to decompose and 
disappear; the nucleus also becomes 
indistinguishable. As soon as the 
germ-tube begins to develope pro- 
toplasm moves into it from the spore. 
In many cases the germ-tube grows 
exclusively at the expense vf tle TEs Bilplespnions Dea axbpsleemucmsrts 
protoplasm and the reserve of food er The stages ofthe development follow the letters. Magn. 390 
in the spore. Germination of this 
kind takes place when water only is present, and succeeds best in water; examples 
of it are to be seen especially in Fungi which lead a purely parasitic life, such as the 
Peronosporeae and Uredineae (Fig. 55); the large spores of Pertusaria, Ochrolechia, 
and Megalospora are also of this kind. In these cases the spores do not increase in 
size after the first formation of germ-tubes; their protoplasm and reserve of food, with 
the exception of an accidental and unimportant residue, passes over into the tubes in 
proportion as they develope; water takes the place of these substances in the original 
spore-cavity, and the spore-membranes thus emptied of their contents soon perish. 
Other spores require a supply of nutrient substances as well as water in normal 
germination, or at least absorb them when present. They then increase consider- 
ably in size and their inner cavity is permanently lined with a layer of protoplasm, 
like a vegetating cell; in other words they are permanently vegetating portions of the 
mycelium that grows out of the spore, and it is not surprising that transverse 
walls should also be sometimes formed in them. Many Mucorini, as Mucor 
stolonifer and M. Mucedo, and the Sclerotinieae, as Sclerotinia Fuckeliana, are 
excellent examples of this kind. Intermediate forms are found, as might be expected, 
between the two extremes. 
[4] ; I 

