224 MISS E. S. BARTON ON THE GENUS TURBINARIA. 
able to place them in the division of which Ascophyllum is the type, in so far as the 
persistence of the initial cell is concerned ; the initial cell divides longitudinally, and both 
cells, after again dividing transversely near the top, grow out into hairs, the upper 
division of the initial cell forming the swollen base of the mature filament (Pl LV. 
figs. 4, 5, 6). These filaments fill the fully-grown conceptacle, and for some time I was 
uncertain whether they were a part of the plant or some parasite alga ; however, develop- 
mental stages prove conclusively the continuity of the filaments with the tissue of the 
thallus. It is difficult to decide their exact length, since the hyaline end is often broken 
off in cutting the section. In comparing the vegetative conceptacle of Turbinaria with 
that of Cystoseira as figured by Dodel-Port (2. c. tab. 4. figs. 5 & 6), the resemblance 
between the two is marked (cf. Pl. LV. fig. 3), but there is a difference in the mode of growth 
of the paraphyses themselves, inasmuch as the upper cells of those in Cystoseira are very 
short, showing acropetal growth (/.c. tab. 5. fig. 3); while in Turbinaria the case is 
reversed and the growth is basipetal. Тһе cells lining the sides of the mature con- 
ceptacle form а papillate layer protruding into the cavity, and resembling the cells lining 
the air-vesicle. (Cf. Pl. LV. figs. 2 & 3.) 
III. Root.—The root is differentiated into three layers of tissue, and resembles in 
structure the base of the petiole near the point of its junction with the main stem. The | 
cortical parenchyma, which is very thin-walled, occupies a large proportion of the whole, 
and the same pits are found in the central strand as those described in the stem and 
petiole. 
Reproductive Organs. 
The receptacles of Turbinaria are in all cases branched and more or less corymbose. 
They arise from the base of the petiole, and, as I have before mentioned, Turbinaria ree 
sembles in this respect the neighbouring genera Sargasswm &c., where the receptacles grow 
indiscriminately on the stalk of the leaf or the vesicle. The growth of the receptacle, 
which resembles in form that of other Fucaceous alge (Pl. LV. fig. 7), is by means of a 
pyramidal, more or less truncated apical cell, lying at the base of a depression, the narrow 
end being uppermost. A comparison of my own figures (Pl. LV. fig. 8а & 5) with that of 
Oltmanns (loc. cit. tab. xi. fig. 7) shows a certain resemblance between the apical cells 
of Turbinaria and Halidrys. In the case of Turbinaria it divides tangentially by walls 
parallel to its three sides, giving off daughter-cells, which form the epidermal layer, and 
these cells, by subsequent perielinal division at their base, cut off others which form the 
cortical parenchyma (Pl. LV. fig. 8а). Segments are also eut off by walls parallel to the base 
of the apical cell, which form the central conducting tissue. This tissue branches from 
the petiole of the leaf into the receptacles, and runs through the centre up to the apex; 
the cortical parenchyma and the epidermis are also continuous from the one into the 
other. The development of the fertile conceptacle I take to be the same as that of the 
vegetative conceptacle, which I have mentioned above. 
As regards the species I have examined, I find that the conceptacles of Turbinaria 
ornata, J. Ag., contain only oogonia, together with branched paraphyses, which, how- 
ever, bear no antheridia ; T. conoides is both hermaphrodite and dicecious, resembling 
