78 BOTANICAL GAZETTE [JULY 
e seem to be three possible sources of the gas in these vesicles: (1) 
atmospheric air, (2) the gases dissolved in the sea water, and (3) gases pro- 
duced in the metabolism of the plants themselves. He excludes (3) because 
he has ‘“‘never detected any gases beyond nitrogen and oxygen in the floats,” 
and “it is hardly conceivable that any process of metabolism should yield 
these two gases only without any carbon compounds.” He excludes (1) 
because his analyses (table I) do not show the nitrogen and oxygen in the 
vesicles to be in the proportion that they are in atmospheric air (79:21), and 
because the gas must be formed in the cavity pari passu with its growth, other- 
wise the vesicles would collapse. 
TABLE I 
ANALYsIS OF GASES IN THE FLOATS OF ALGAE 
Species hyena of aa oon A of Comments 
Phyllospora comosa (1)..... 86.0 14.0 Fresh-looking plants cast 
up o 
. ie ee oe ane 10.6 Just cast up 
ypc | Aare 88.9 tr. Piece less 
6 it4 (4) 82.3 17.7 sc “ ce 
as Wo tel: ace 16.8 ee 
Hormosira Banksii (1)..... 88.46 II.54 Growing 
- MAS ep Pee? 88.0 12.0 Same gathering kept a day 
longer 
Cystophora monilifera...... 80.0 20.0 Floating in the sea 
TABLE II 
ANALYSIS OF GAS OBTAINED BY BOILING IT OFF FROM WAVE-WATER FROM THE OCEAN 
(a) (8) 
aia Spies hi oracle Rs 67.12 58.33 
De es SACU eras 26.03 30.55 
Citbon dioxide ia gos aes 6.85 be ae 
He notes that in the analyses of surface waters collected by the “Chal- 
enger” the proportion of nitrogen to oxygen varied around a mean of 2:1, 
and that this would be expected from the relative solubility of the two gases. 
He accepts (2), although his table does not show the proportion of nitrogen 
and oxygen to be the proportion that he has found in sea water gas (table ID), 
and although he finds considerable carbon dioxide in sea water gas and none 
in the gas from vesicles. He observes that the presence of organisms seems 
to alter the natural ratio of the gases dissolved from the air. He believes that 
the gas enters, dissolved in the water, by osmosis, and that just as marine algae 
show a marked preference for potassium sulphate and commonly reject much 
of the sodium chloride, so they may show a marked preference for oxygen, and 
