Mutinu $ caninus (. Huds .), 367 
the walls of the chambers, increase greatly in size, and it 
becomes difficult to conceive of their having originated by 
lateral inflation of hyphae. The growth of the walls is more 
rapid than that of the tissue of the chambers, and, as a result, 
the even-surfaced chamber-walls of Fig. 11 are thrown into 
a series of folds like those of a Chinese lantern, to use the old 
illustration. As the growth in length of the stipe after the 
folding of the chamber-walls still continues to be more rapid 
than the growth in length of the egg, the wall of the stipe 
as a whole becomes thrown into a series of folds in this 
species. 
In these changes the intermediate tissue A and the tissue 
of the chambers become torn, the latter tissue and that of the 
central column become more highly gelatinous, and the gleba 
splits away from the volva in the plane of the inner layer of 
the latter. During this last change, the volva is burst open 
at its apex by the receptaculum, which gradually pushes its 
way up through the opening by the straightening out of its 
folded walls. It is now believed that the straightening out of 
the folded walls and consequent elongation of the stipe is due 
to changes in the form of the cells situated at the inner and 
outer surfaces of each angle of each fold. At the inner 
surface of the angle, the cells are wedge-shaped as though by 
compression ; on the outer surface, they are elongated and 
flattened as though by a pull longitudinally. Both of these 
sets of cells become more spherical in form during elongation 
of the stipe. Such a change in the form of the cells at the 
inner surface of the angle must tend to lengthen that surface 
and so straighten out the fold ; the change in form of the 
cells on the outer surface of the angle must tend to shorten 
that surface and so help straighten the fold. The changes in 
form of the cells on both surfaces of each cell therefore work 
together in straightening the fold. In Errera’s paper taking 
up this subject, the change in form of the cells at the angles 
of the folds is regarded as due to a true process of growth 1 . 
1 L. Errera, Sur le glycogene chez les Basidiomycetes. Memoires de l’Acad. 
roy. de Belgique, t. XXXVII, (1885), p. 52 of reprint. 
