THE 
New Phytologist 
Vol. XVIII, No. 8. 
October, 1919. 
[Published December 4th, 1919.] 
THE IONIC PHASE OP THE SEA. 
Bv A. H. Church. 
O the subaerial botanist brought up on an extended course of 
laboratory cultures involving a “food-solution” with the 
extreme dilution of about 3| grams per litre, sea-water with 3£% 
of salts, or just ten times the amount, appears as a strongly plasmo- 
lytic solution, the utility of which as a nutritive medium seems 
almost ludicrous in view of an osmotic value of over 20 atmospheres, 
great content of common salt, and microscopic proportions of com¬ 
pounds of Nitrogen and Phosphorus. Such an attitude is reflected 
in the discussion of the problems of halophytes, and one is asked to 
admire the biological equipment of such plants as Salicornia and 
Sues da fruticosa in this country, or the more arboreal Mangroves 
(RhizopJiora and Avicennia) established in forest-association in the 
seas of more tropical latitudes; though further out one is brought 
into contact with Zostera, an Angiosperm living permanently 
submerged in the sea on our own coasts ; while Posidonia, a possibly 
allied form, extends commonly to 30 fathoms in the clear water of 
of the Mediterranean, and Schimper does not scruple to record it at 
50. The continued existence of such plant-forms which derive 
their sustenance from a substratum soaked in sea-water, leads on to 
the recognition of the fact that in the case of the benthic (algal) 
vegetation of the sea, as “ hormon ” or anchored somata without 
absorptive roots, the sea does represent the actual food-solution 
of the entire series of marine algae, as in fact it is the sole food- 
solution of all earlier phyla of simple plankton-forms. At last it 
begins to be realized that the sea may not only be on occasion a 
food-solution to higher organism, but that it is the essential and 
only food-solution of all primitive forms of plant-life ; and not only 
the sole source of food-salts, but at once the actual and original 
medium permeating the entire body of marine organisms ; that is 
to say, the medium from which they draw all supplies of food- 
materials, and even the medium in which all the cytoplasmic 
