BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND. 9. N:0 9. 9 
Al: Br.). The conjugation is in this species, as is known, 
often longitudinal (i. e. between 2 cells belonging to the 
same filament and abutting on each other). In the case of 
longitudinal conjugation which I have represented fig. 19, 
the septum in the connecting canal has never been re- 
sorbed, and consequently there has been no possibility of a 
connubium taking place. Nevertheless, the chlorophyllaceous 
bodies in the two conjugating cells have moved into the 
conjugation-outgrowths, after which the chlorophyll-filled part 
of each cell has been confined by a septum. In this manner 
two parthenospores have, as the figure quoted above shows, 
been made to lie close to each other in the intended canal 
of conjugation. — 
In all the manners of spore-formation in Mesocarpew de- 
seribed above, the spores have been formed after a fecunda- 
tion, or at least by cells which were meant to be fructifica- 
tive. But in the case of spore-formation which I am now 
goimg to discribe, the spore-formation seems to me to take 
place in a purely neutral way, through the agency of cells 
which have never had the power of nor been meant for con- 
jugation. The plant which has given me opportunity to make 
the observations written below has grown during this antumn 
(the months of October and November) in an aquarium in 
the warm-house belonging to the botanical garden of Upsala. 
My attention was called to the plant by Prof. TH. M. FRIes, 
who did also with great Iiberality place at my disposal an 
excellent material for examination gathered there by him. 
This plant — which I believe to be new to science and to 
which I have given the name of Gonatonema ventricosum -—— 
showing several interesting peculiarities, I will here give a 
somewhat detailed exposition of its structure and of its life, 
as far as it is known to me. 
On its vegetative stage Gonatonema ventricosum consists, 
as well as the other Mesocarpew, of cylindric cells arranged 
in a single tow; see figs. 1, 2 and 3. The membrane of the 
cells is very thin and consists of pure cellulose. The bottoms 
of somewhat older cells are gently curved inwards, which 
gives rise to a small lense-shaped room between the cells. 
The contents of the cells consist of 1:o a parietal, thin, 
colourless layer of protoplasm, 2:o an axile, chlorophyll- 
