104 DIVISION I.—GENERAL MORPHOLOGY, 
mentioned also the envelope-cells on the spore-clusters of Urocystis, which will be 
described in Chapter V, but not the germ-tubes which appear inside the ascus 
in Sphaeria praecox, and which were described by Tulasne ! as filiform appendages. 
We have already spoken, in concurrence with Zopf’s views, of the physiological 
import of the gelatinous appendages as organs which may serve to attach the asco- 
spores to one another and to the apex of the expanding ascus. This is evident 
in the case of the Sordarieae, in which the spores, each with its dark episporium, lie in 
a row in the ascus one behind the other and in contact with one another, and the 
conical gelatinous processes on each spore are firmly attached to those of its next 



FIG. 52. Sordaria. ‘seda, de Not. D of the spores, the successive stages in the order of the letters. a—y 
from recently isolated uninjured asci; /a fully developed spore but with the yellowish brown membrane still transparent and 
the germ-pore visibleabove. ga ripe spore escaped from the ascus, with its membrane of a violet black colour. Magn. 390 
times, 
neighbour or are twisted round them. How far the function of these appendages is 
the same in other cases is a question which requires further careful investigation. 
Of the chemical nature of the spore-membrane only some isolated facts are known, 
and the subject is still in need of more thorough examination. Hoffmann” has 
collected together a variety of details on this subject. 
Most spore-membranes, according to the concurrent testimony of all observers, 
are distinguished by their great power of resisting decomposition and the influence of 
strong reagents, more especially concentrated mineral acids. Many are only slightly 

1 Carp. I p. 80. 
2 Pringsheim’s Jahrb. II, p. 308. 
