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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 57
BULBOCOLEON, Pringsh.
(From βολβος [bolbos], a bulb, and κολεον [koleon], a sheath.)
Filaments branching, creeping, composed of two kinds of cells, one producing
numerous zoospores, the other bulbous at the base but drawn out into a tube, from
the open extremity of which projects a long flexible hair.
This genus, consisting of a single species, was first described by Pringsheim in the Abhandlungen der
königl. Akademie der Wissenschaften, Berlin, 1862, who founded it upon a small alga parasitic in the
fronds of Leathesia and other Phæosporeæ, at Helgoland.
The genus resembles Coleochæte, a fresh-water genus, in the structure of the hairs, but in Bulbocoleon
no reproductive bodies, except zoospores produced in the ordinary cells, have as yet been discovered. It
is not impossible that oospores may at some time be found, and it will then be necessary to remove the
genus from the present order.
B. PILIFERUM, Pringsheim, l. c., p. 8, Pl. I.
Characters same as those of the genus.
Parasitic in the fronds of Leathesia tuberiformis and Chordaria divaricata. Summer.
Newport, R. I.; Wood’s Holl, Gloucester, Mass.; Europe.
This minute species is found creeping among the cortical cells of Leathesia and Chordaria, generally in
company with a Streblonema. It forms dark spots on the fronds, and, on microscopic examination, the
hyaline hairs are seen projecting above the surface. The species is studied with difficulty when
parasitic on Leathesia, owing to the density of the cortical part of the frond, but is more easily
examined when it grows on Chordaria. It was found by Pringsheim on Chorda filum, Chordaria
flagelliformis, and Mesogloia vermicularis, as well as on Leathesia. It probably will be found on several
other Phæosporeæ of our coast, where it appears to be common.
The following genus described by Reinsch, including a species of which we have not been able to
examine specimens, should be included in the account of the Chlorosporeæ of our coast:
ACROBLASTE, new genus of Chroolepideæ.
Plants microscopic, marine, forming densely aggregated tufts attached to stones and shells; threads
erect, subsimple, branching from the base, arising from procumbent, densely interlaced threads;
conceptacles in the upper part of the branches nearly spherical, at first unicellular, afterwards
producing 20-35 spherical zoospores; after the discharge of zoospores elliptical, with a wide mouth;
development of the branches and growth of the threads as in Chroolepus and Cladophora.
Acroblaste, spec. Contents of cells finely granular, distinctly circumscribed; color slightly glaucous
green; cell-wall thick, sublamellated, twice as long as broad.
Height of plant, .336-.6 mm .
Diameter of filaments, .0050-80 mm .
Diameter of conceptacles, .0168-196 mm .
Diameter of zoospores, .0022 mm .
Hab.—Attached to shells and stones, Buzzard’s Bay, Mass.
Reinsch., in Botanische Zeitung, 1879, No. 23, Pl. 3 a.