g6 Sturch . — Harvey ella mirabilis ( Schmitz & Reinke). 
cells interspersed, and also the attenuated cells derived from 
the same original peripheral cell as the tetrasporangium, this 
layer being continuous over the whole surface of the external 
frond (Fig. 7). Tetraspore- bearing fronds, which are rare, are 
found in the spring. 
The method of preparation adopted was to fix fresh material 
in a saturated solution of corrosive sublimate in sea-water, 
and then to cut fairly thick sections in mucilage on a freezing- 
microtome. The sections were afterwards stained with 
Hoffmann’s blue in equal parts of glycerin and water. If the 
cell-contents become much contracted, they can be swollen 
out to their original size by gently warming the section. 
The two sterile filaments, which are derived from the 
auxiliary cell in Harvey ella mirabilis , and whose function is 
probably nutritive, are similar in character to those described 
for various species of the Rhodymeniales by Professor Phillips. 
For comparison I have added a short summary of the characters 
of these sterile filaments, taken from Professor Phillips’ paper 
on the Rhodomelaceae 1 : — 
£ Sterile branches — two such invariably present. 
£ In Rhodomela and Polysiphonia — inferior branch 1 -celled, 
lateral branch 2-celled at fertilization of the trichogyne, 
becoming 2-celled and 4-celled later. 
£ In Chondria and Laurencia both branches are luxuriantly 
branched at the time of fertilization, developing but little 
afterwards, and becoming partially absorbed on spore- 
formation. 
‘ In Dasya the two branches are but slightly represented, if 
at all, at the time of fertilization, but become richly branched 
afterwards, still before spore-formation sets in.’ 
In Harvey ella mirabilis the branches are respectively 2- and 
4-celled, are developed before fertilization of the trichogyne, 
and are again absorbed by the auxiliary cell after fusion 
with the carpogonium and before the development of the 
gonimoblast. 
1 Development of the Cystocarp in Rhodomelaceae (II), Phillips, Annals of 
Botany, Vol. X, 1896, p. 201. 
