Cystocarp in Rhodomelaceae ( 77 ). 189 
commonly occurs in Rhodomela subfusca , where the unfertilized 
procarps become transformed into axes of limited growth. It 
has occurred to me that as branches in various Rhodomelaceae 
are borne upon the persistent basal cells of the leaves (9), the 
same process may occur in Rhodomela , and the metamorphosis 
into a branch of a procarp that has remained unfertilized, 
may be due to the sprouting of the lowest joint. 
The procarps of Dasya are much more compact and opaque 
than those of other plants of the family which I have examined. 
The cell-wall does not swell equally under treatment with 
glycerine, and I have found the examination of the procarps 
in an entire condition very tedious and troublesome. Latterly 
I have adopted the practice of passing material preserved 
in formaldehyde into a weak solution of gum-arabic, and 
making sections with the aid of a freezing microtome. For 
the study of the later stages in the development, when it 
becomes still more opaque, some method of section-cutting 
becomes absolutely necessary. Sections cut in frozen gum 
may afterwards be washed free from the gum, stained in 
Hoffmann’s blue or some other suitable stain, and mounted 
for examination in strong glycerine. Sections obtained by 
cutting in paraffin offer no advantages for the purposes here 
in contemplation, viz. the tracing of the genetic relationship 
of the contents of the cystocarp. Provided that the sections 
are not opaque, the thicker they are, the better for the 
purpose of the investigation. When, however, other problems 
come to be solved, such as the structure and behaviour of the 
nucleus in the cells concerned in reproduction, section in 
paraffin, to which the material readily lends itself, will be 
found the only available method. The figures of Dasya , 
however, accompanying this paper have been obtained from 
material fixed in formaldehyde, cut in frozen gum, stained in 
Hoffmann’s blue, and mounted in strong glycerine. 
The central cell of the joint which bears the procarps gives 
off five pericentral cells, and it is the fifth, occupying the 
median position above (towards the sympodial axis), which 
gives rise to the essential structures of the procarp. It is 
