Grinnellia americana y Harv . 19 
and possess a clear granular appearance. Presently they 
enlarge (Fig. 26 cp\ passing through an elongated oblong- 
elliptical form (Fig. 26 c') to a true oval or spherical shape 
(Fig. 2 6 m). As the spores gradually increase in size, they 
acquire a reddish colour which finally becomes a lake-red, 
the characteristic colour of all mature spores of Grinnellia . 
This process is repeated by every one of the sporiferous 
filaments developing from the large central basal cell, in this 
way giving rise to a very large number of carpospores, 
averaging from 300 to 400, in every mature cystocarp. The 
stimulation resulting from fertilization of the young cystocarp 
is manifest not only in the origin and active growth of the 
sporiferous filaments, but also in the rapid development of 
other portions, such as the pericarp, basal cortical tissue and 
sterile filaments (Fig. 21). 
From the moment the joint-cell at the base of the procarpic 
branch begins to enlarge and acquire dense protoplasmic 
contents, the growth of the pericarp is accelerated. The cells 
on the upper surface of the cystocarp multiply rapidly and 
become elevated by the growth of tissue in the fruiting portion 
of the young cystocarp. As this surface-tissue, which is to 
form the pericarp, further develops, it is apparent that its 
irregular arrangement of cells is becoming regular, and that 
a number of filaments, growing apically, are united with each 
other by lateral branches. These pericarpic filaments not 
only branch in the surface-plane of the pericarp, but also at 
right angles to that plane, forming two- to three-celled branches 
which are connected with the terminal cells of the sterile 
filaments within the cystocarpic cavity (Fig. 18 sp). The 
branches from the pericarpic filaments decrease as the filaments 
grow outward and upward until their apices are in contact and 
form a circle about an open portion over the central region 
of the cystocarpic cavity. These filaments now change the 
direction of growth, which had previously formed an angle 
of 6o° to 75 0 with the surface-plane of the frond, so that they 
grow almost at right angles with that surface (Fig. 22 cr). 
The apical cells divide four to six times and growth dis- 
