MISS E. 5. BARTON ОХ THE GENUS TURBINARIA. 221 
sporophyte. According to this plan the respective organs of Turbinaria would fall under 
this new terminology ; but, without disputing the advantages of such a plan, I think the 
words “leaf” and “stem” will serve my purpose equally well, the more so since Prof. 
Bower does not exclude the propriety of so using them. 
I have compared Turbinaria with specimens in the British Museum Herbarium of the 
genera most nearly allied to it, viz. :—Sargassum, Carpophyllum, Cystophora, Cystoseira, 
and Oystophyllum. Each of these shows air-vesicles distinct from the leaf, but since, in 
many cases, I find the receptacles growing on either indiscriminately, I regard the vesicle 
as a metamorphosed leaf in all cases. A further proof of this is found in the fact that 
the vesicle in Cystoseira Lepidium, Anthophycus longifolium, and Sargassum linifolium 
is sometimes prolonged into a foliar structure, and sometimes again forms the central 
portion of a flattened leaf, showing that part of the leaf has become metamorphosed to 
form an air-float (see Kiitz. Tab. Phyc. Bd. x. tab. 64, and Bd. xi. tab. 24). Іп the case 
of Turbinaria these two leaf-forms are represented іп one, which unites in itself the two 
functions of an assimilative organ and of an air-vesicle. 
I. Stem.—The main stem is composed of three distinct layers of tissue (Pl. LIV. fig. 6), as 
described by Wille (“От Fucaceernes Blaerer,” in Bihang till K. Svenska Vet. Akad. Hand- 
lingar, Bd. 14. Afd. iii. no. 4, Stockholm, 1889) in speaking of Halidrys siliquosa. The 
epidermal layer consists of the usual narrow radially elongated cells; beneath this is a band 
of thick-walled cortical parenchyma, which gradually passes over into the central strand 
or fascicular tissue. "This latter occupies by far the largest proportion of the whole stem, 
and forms a thick strand of long narrow cells, resembling a vascular bundle of the higher 
plants, and probably, like it, performing the double office of supporting and of conducting 
tissue (Pl. LIV. figs. 7 & 8). The transverse walls of this tissue are extremely thin, and 
both in these and in the pits on the longitudinal walls there are perforations, through which 
I find that the protoplasm is continuous. Though 1. had at first suspected that the thin 
places in the cell-walls of this central strand were perforated, I was unable to prove it 
until I treated several sections after the method employed with so much success by 
Mr. Gardiner (Phil. Trans. Royal бос. 1883, р. 821) on the endosperm of Palms, the pulvini 
of sensitive plants, &c. The section was soaked for a few seconds in strong sulphuric acid, 
then washed thoroughly in distilled water, after which I stained it with picric aniline 
blue. The sulphuric acid caused the cell-walls to swell, and the strands of protoplasm 
were seen passing in thin threads through the sieve-like perforations of the pits. This 
continuity is more plainly visible in the stem than in any other part of the plant, but this 
is possibly owing to the fact that the cell-contents were here better preserved. 
Apex.—As regards the growth of Turbinaria I am only able to say that it is apical, but 
whether it is by means of a single cell or a group of initial cells the material at my 
disposal has not made it possible for me to decide. The meristematic region, as 1n other 
Ғасасеге, lies at the base of а depression covered in with young leaves deusely crowded 
together, thus rendering the investigation of the growing point more difficult. 1 hope, 
however, at some future time, when I shall have more material suited for such investi- 
gation, to carry it out in its fullest details. The analogy of the receptacle to be subse- 
quently described would lead us to expect a single apical cell in the vegetative stem also. 
