ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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tlic formation of the zoospores of Cheetomorpha aerea, Acetabularia 
mediterranean Codium tomentosum , and Halimeda Tuna , or in which the 
entire protoplast is divided into numerous smaller ones, as in the forma- 
tion of the swarm-cells of Sporochnus pedunculate, Arthocladia villosa , 
and Derbesia Lamourouxii. The young sporange contains a central 
vacuole and a parietal layer with imbedded chromatophores, and one or 
more nuclei. As the nuclei and chromatophores multiply, strings or 
plates of protoplasm are formed traversing the vacuole and breaking it 
up. The chromatophores, each with its own nucleus, vacuoles, and 
cytoplasm, collect into small groups ; between these groups colourless 
lines make their appearance, and each protoplast thus formed dcvelopes 
into a zoospore. The antherozoids of the Fucaceas are formed in the 
same way. 
A third group consists of plurilocular sporanges, of which Lctocarpus 
confervoides may be taken as a type. A cell containing a parietal layer 
of protoplasm, with chromatophores, nucleus and vacuole, divides into a 
mass of cells, each of which again contains, as the result of division, 
all the organs of the protoplasm. The contents of each cell becomes a 
zoospore. Similar phenomena characterize the formation of the polli- 
noids of the Floridese, and the antherozoids of the Characeae and of the 
higher Cryptogams. 
In the gemmae of such algae as Sphacelaria tribuloides each cell 
contains a nucleus and a layer of protoplasm with chromatophores and 
vacuoles, which bodies have been formed by division out of the mother- 
cells of the gemma. 
Lemaneaceae.* — Prof. G. F. Atkinson publishes a monograph of the 
United States’ species of Lemaneaceae, which he unites into the single 
genus Lemanea , of which he describes seven species, five belonging to 
the subgenus Lemanea proper (two of them new), and two to the sub- 
genus Sacheria, with several varieties. 
The oophyte has three distinct successional forms : — (1) A permanent 
cellular or confervoid prostrate form, the former consisting of an irre- 
gular mass of polyhedral cells spread 'over the surfaces of rocks ; (2) a 
Chantransia- form, usually developed as erect lateral shoots from the 
prostrate form, rarely direct from the spore; it consists of branched 
filaments composed of a single series of elongated cells, the endochrome 
in some species coloured violet ; but does not produce gonids ; these 
two forms constitute the protoneme of the plant ; (3) the sexual shoot, 
originating as a special lateral shoot from the Chantransia- form. This 
is a hollow or tubular shoot, containing a system of delicate filaments, 
the apparatus for fructification. The wall is more or less cartilaginous, 
and is composed of three layers — the medullary, consisting of a single 
layer of comparatively large cells, an intermediate layer of somewhat 
smaller polyhedral cells, and a cortical layer of small prismatic cells, 
rich in colouring matter. It derives its nourishment from the Chan - 
transia-iorm, but soon becomes independent by the development of 
rhizoids at its base. The apparatus for fructification consists of a 
central axis, ray-cells, and generative filaments, with the tie-cells which 
unite them to the medullary layer. The development of each of the 
* Ann. of Bot., iv. (1890) pp. 177-229 (3 pis.). 
