Lemaneaceae of the United States . 185 
characteristic cells. The elements composing the medullary 
and intermediate layers show large spaces, while the cells of 
the cortical layer are compactly arranged. The cells excrete 
a mucilaginous substance which fills the intercellular spaces, 
surrounds the entire sexual shoot during its growth, and soon 
fills the interior after the cavity is formed. 
The sexual shoot derives its nourishment first from the 
Ch an transia-io r m from which it arises as a branch. It soon 
becomes independent by the development of rhizoids at its 
base, which form a dense tangled mass with the decreasing 
elements of the Chantransia-iorm. It must be examined 
while still quite young to observe its origin from the Chan - 
transia- form. In Fig. 8 these slender hyaline rhizoids are 
illustrated. About the time of anthesis, or later, the cells of 
the medullary, and sometimes of the intermediate, layer 
develop confervoid filaments, which in some cases are very 
numerous on the interior of the sexual shoot. 
Apparatus of fructification. The apparatus of fructification 
situated on the interior of the hollow sexual shoot consists of 
a central axis, ray-cells 1 , and generative filaments 2 , with the 
tie-cells which unite the generative filaments with the medul- 
lary layer. 
The central axis extends the entire length of the cavity. 
It is composed of a single series of cells placed end to end. 
Fig. 11 represents a portion of a longitudinal section of a 
sexual shoot, a little more than half of the interval between 
two adjacent whorls of papillae ; a is the central axis. It will 
be seen that the cell a articulates with the cell directly below 
it in the middle of an interval between two adjacent whorls of 
papillae. Just below this articulation there are four ray-cells 
branching perpendicularly from the central axis, in the form 
of a maltese cross : x, the generative filaments arise, from the 
1 Sirodot, Ann. d. Sci. Nat., loc. cit., ‘ramification cruciforme ; ’ Ketel, loc. 
cit. , ‘ Stutzzellen.’ 
2 Sirodot, loc. cit, ‘tubes lateraux,’ or ‘tubes placentales ; ’ Ketel, loc. cit., 
‘ wandstandige Zellreihen.’ I have termed them generative filaments because they 
give origin to the reproductive organs. 
