522 Hodgetts—A New Species of Spirogyra. 
to a single cell of a filament, and in several cases it was clearly seen that 
these curved cells were coiled round another filament of the same species . 
This can hardly be considered accidental, and it appears that this coiling 
may be a contact phenomenon serving to grapple the filaments together, 
and thus aiding scalariform conjugation. 
Three modes of conjugation were observed in this species : (i) scalari- 
form conjugation (Photos i and 7, PI. XXII), which was frequent ; (2) lateral 
conjugation — the conjugation-tubes either growing round the clamp- 
connexion, or else piercing it laterally (Photo 2, PL XXII) ; and (3) terminal 
conjugation. The last, and most interesting, method is brought about by 
the growing out of one extremity of a cell, in the form of a conjugation- 
tube, through the septum of the H -shaped clamp, to meet, and eventually 
fuse with, another terminal conjugation-tube put out by the adjacent cell 
of the same filament. Photos 1, 3, 5 to 8, PI. XXII, show examples of terminal 
and subterminal conjugation, these being the methods which were most 
frequently observed. In both it will be seen that the two conjugating-cells 
are pushed some distance apart by the growing out of the terminal or sub- 
terminal conjugation-tubes; and the H -shaped connecting-clamp, through 
the septum of which one of the conjugation -tubes has to pass, is either 
pushed off both the cells and remains transfixed somewhere on the conjuga- 
tion-tube — shown very well by Photo 8, PI. XXII — or else it persists on the 
end of one of the cells, as shown in Photos 6, 7, and in Text-fig. 5. 
True lateral conjugation, such as is shown in Photo 2, PL XXII, was 
rather rarely met with, but all stages intermediate between exactly 
terminal conjugation (as shown in Photo 8) and typical lateral conjugation 
(Photo 2) were observed, and indeed were very frequent. Subterminal 
conjugation is illustrated in the upper part of Photo 1 , PL XXI I, and also by 
Photo 5. It must therefore be understood that the terms ‘ lateral ’ and 
‘ terminal * as applied to modes of conjugation in this species simply denote 
extreme cases of what amounts practically to one and the same method. 
Photo 4 shows an example (on the left) of subterminal conjugation, 
but the central (immature) zygospore has been .produced by a combination 
of the scalariform and terminal methods, the conjugation-tube put out from 
the female gametangium — which is the end-cell of a filament — being 
approximately terminal. This, however, is an abnormal mode of conjuga- 
tion, and was observed only twice. 
Terminal (or subterminal) conjugation does not appear to have been 
described as a normal method of conjugation in any other species of 
Spirogyra , as far as the present writer is aware. It should be noted that 
an attempt at this method of conjugation in any other species of the genus 
— whether provided with replicate end-walls or not — would probably fail 
owing to the two conjugating-cells being pushed apart before a firm union 
became established between the conjugation-tubes. In the present species, 
