146 SIPHOPHYCEX, 
Famity IV. PITHOPHORACE A. 
Chlorophylliferons Cladophora-like Fresh-water Algz, con- 
sisting of cells formed by bipartition of the terminal cell, the 
thallus having two distinct parts—(1) the cauloid part, 
developed from the germinated spore upwards, propagative, and 
almost always branched, the branches placed a little space 
below the top of their supporting cells ; (2) the rhizoid part 
developed from the germinated spore downwards, almost always 
sterile and branchless, commonly unicellular. Spores neutral, 
quiescent (agamo-hypnospores), generally cask-shaped, single, 
formed by division into two of the cauloid cells, of the chloro- 
phyll filled, and commonly widened upper parts of these cells; 
in germinating, as a rule, dividing into two cells, the one 
giving rise to the cauloid and the other to the rhizoid part 
of the thallus.— Wittrock, Monograph of the Pithophoracee, 
p. 46. 
For full details of this Family, consult Prof. V. B. Wittrock “On the 
Development and Systematic Arrangement of the Pithophoracee ” (pub- 
lished in English). Upsal, 1877. 
GENUS 68, PITHOPHORA. Wittr. (1877.) 
Character the same as that of the family given above. 
The formation of spores is effected in the following manner:—The 
upper part, 4-4 of the mother cell of the spore, is somewhat widened. 
The chlorophyll-coloured protoplasm in the lower, not widened, part of 
the cell then passes little by little into the upper and widened part, till it 
is quite filled with chlorophyll-coloured protoplasm. A transversal cell 
wall is then little by little formed just below the point where the 
widened part of the cell commences. In this manner are formed one 
lower cell containing but little protoplasm, almost devoid of chlorophyll, 
the so-called subsporal cell, and one upper cell, rich in chlorophyll and 
reproductive, the spore. Its shape is,as a rule, cask-like or cylindri- 
cally cask-like. When the membrane of the spore has attained a not 
inconsiderable increase in thickness the spore reposes some time before 
germinating, and consequently belongs to the class of spores which is 
called hypnospores. With regard to its origin, it may be called an 
agamo-spore, as being formed neutrally without any fecundation. 
Formation of spores may take place in all the cells of the cauloid, in the 
terminal as well as in theinclosed. As a rule it begins in the youngest, 
i.e, the terminal cells; afterwards proceeding downwards, or, in other 
words, basipetally, in the principal filament as well as in the branches. 
It is these spores which give origin by their germination to the course of 
development already described. In this manner you will see one neutral 
generation, forming hypuospores, follow upon another, in an uninter- 
rupted series, without any metagenesis. 
