90 Sturch. — Harveyella mirabilis ( Schmitz & Reinke). 
surrounded by and are eventually 
isolated among the cells of the external portion of the parasite 
(Fig. 3). These cells are well shown in Kuckuck’s paper 
on Choreocolax albus. They often remain for some time, 
but their contents are eventually absorbed, and their walls 
collapse. They are sometimes carried up by the growth 
of the parasite almost to its peripheral layer. 
When the Harveyella is fully grown, it commences to 
develop antheridia and trichogynes. The earliest indications 
of the presence of Harveyella - filaments in the Rhodomela - stems 
were noticed on October 4, when the parasite was in the 
stage shown in Fig. 1 . The first appearance of very young 
antheridial fronds was on October 23, and by the second 
week in November they had become very numerous, tricho- 
gynes appearing on other fronds at about the same time. 
The antheridia have been previously described as occurring 
on small, flat fronds 1 ; but the antheridial fronds which I 
have found are of all sizes, being very frequently as large 
and spherical as the mature cystocarpic fronds. The an- 
theridia are developed over the whole surface of the frond. 
The first indication of them is that the distal cells of the 
peripheral chains are elongated and divided by oblique 
curved longitudinal walls producing a small tuft of two or 
three very narrow cells (Fig. 5, a). These cells then cut off 
successively, at their distal ends, small more or less spherical 
cells (Fig. 5,#); so that, when mature, the whole surface 
of the antheridial frond is covered by a layer, three or four 
deep, of these small cells, embedded in the gelatinous external 
membrane. They are set free by the breaking away of this 
membrane. 
The first trichogynes were noticed at the beginning of 
November, that is to say, one month after the parasite was 
first seen. The trichogyne is developed from a growing 
peripheral cell. As this cell commences to elongate at its 
upper end, three small cells are cut off successively at its base. 
1 Schmitz and Hauptfleisch, Die Natiirlichen Pflanzenfamilien, Engler and 
Prantl. 
