A New Species of Spirogyra. 
BY 
WILLIAM J. HODGET.TS, M.Sc. 
With Plate XXII and five Figures in the Text. 
URING May, 1919, a number of species of Spirogyra (including 
Jl-J S. calospora , orbicularis, nitida , long at a, catenae for mis, inflat a, &c.) 
were observed in conjugation in a pond, which has been visited periodically 
for some time, at King’s Norton, near Birmingham, and amongst these and 
other filamentous Algae occurred a Spirogyra , which not only appears to 
be a new species, but which presents several interesting features hitherto 
undescribed for the genus. 
The vegetative cells of this species are 29-40 /x wide, while their length 
is 8-16 (sometimes as much as 22) times as great as the diameter. The 
filaments always show a conspicuous gelatinous sheath, which, even without 
the aid of stains, usually exhibits a very well-marked fibrillar structure (cf. 
Text-fig. 4). On mounting filaments in Indian ink it is easily seen that 
this sheath consists of two layers, and that the outer layer shows no obvious 
structure, the fibrillae being confined to the inner' layer, which is also some- 
what thicker than the outer. These fibrillae — which, of course, occur in the 
sheaths of certain other filamentous Conjugates, as well as in those of some 
Desmids — have a remarkable resemblance to large rod-shaped Bacteria, 
and give the filaments quite a furry appearance — shown in Photo 1, 
PI. XXII ; if a hand-lens is used, however, the fibrillar structure will be 
obvious in this photograph. It was rare for the whole sheath to be 
apparently structureless. 
The most curious feature, however, is the development between every 
contiguous pair of cells of an H -shaped piece of membrane, connecting the 
two cells together like a clamp (see Text-figs. 3, 4). This connecting- 
clamp is a thin cylindrical piece of cell-wall, 25-30 /x long, and furnished in 
the middle with a thin septum, so that the appearance in optical section is 
like the letter H. Although it gives the reaction for cellulose like the rest 
of the cell-^all, the longitudinal portion of the clamp-like connecting-piece 
is rather thinner than the main cell-wall, while its transverse septum is 
extremely thin. Each half of the connecting-piece fits tightly like a cap 
(Annals of Botany, Vol. XXXIV. No. CXXXVI. October, 1920.] 
