693 
Costaria, Undaria, and Laminaria. 
from the germinating spore till the simple Laminarioid frond is completed, 
with its various medullary, cortical, and epidermal tissues. Reinke 1 insists 
upon the term ‘ embryonal stages ’ for all those before sorus-formation. In 
the present paper the term is taken as by Setchell, but a little extended ; 
viz. from the sporeling up to the time when all the organs (the sorus 
excepted) found in matured plants have been indicated, though in a primitive 
state. 
The youngest stage of Costaria Turneri that I could find was a con- 
fervoid body measuring about 70 ju, in length (PI. LIII, Fig. 1). It was 
a simple filament of seven cells disposed in a row. The cells were cylindrical 
without any marked constrictions at the septal points, and the length was 
nearly equal to the diameter. The apical cell was more or less elongated 
compared with the rest, and was slightly swollen, with a round head- 
Chromoplasts were present in each cell, filling up nearly the whole room in 
the terminal cell, but rather poor in the others. The basal part of the 
confervoid body could not be examined in a satisfactory manner, as this 
portion was entirely hidden in the interwoven filaments of Sphacelaria , 
Ulothrix , &c. Judging, however, from observations on the later stages, it is 
very likely that the lowermost cell of the confervoid body is elongated into 
a long siphonal tube penetrating the felty substratum. 
The growth of the confervoid body in length results from successive 
divisions of the apical cell in transversal planes perpendicular to the axis of 
the filament. 
Areschoug 2 described the sporelings of Chorda tomentosa as becoming 
simple or branched monosiphonous filaments. Similar sporelings have been 
observed by Williams 3 in certain members of the Laminariaceae, and by 
Okamura 4 in Leathesia. Kiitzing 5 delineated three very young stages of 
Laminaria saccharina growing in association. In his figure he indicated the 
confervoid, branching bodies at the base of a young plant. He does not 
mention them as young stages of the plant, remarking simply: ‘ Conferva- 
artige Faden, welche den protonematischen Bildungen der Moose ahnlich 
sind.’ It is very probable, however, that he regarded these bodies as the 
primary stage of the plant jointly illustrated with them. These facts might 
suffice to convince us that various brown Algae of three dimensions are at 
the beginning confervoid. In Saccorhiza bulbosa , according to observations 
by Thuret, 6 the monosiphonous filament does not branch at all, and ceases 
to add to its own length after there are half a dozen cells in a row. 
The zoospores of Costaria Turneri are freed from the mother frond late 
1 Reinke: Studien zur vergleichenden Entwicklungsgeschichte der Laminariaceen, 1903, p. 11. 
2 Areschoug: Observationes Phycoh, iii, p. 15, Tab. I, Fig. 1. 
3 Williams: Nature, vol. lxii, p. 613. 
4 Okamura: Icon, of Japan. Algae, vol. i, No. 4, PI. XVIII, Figs. 10-12, 
6 Kiitzing : Phycol. Generalis, p. 345, PI. XXIV, I, Fig. 5. 
6 Thuret: 1 . c., PI. XXX, Fig. 10. 
