280 MISS SARAH M. BAKER ON THE 
. Pelvetia (loose) laid on wool. Na,HPO, 0*5 grm. per litre. 
.. Pelvetia (cut off stones) laid on wool. КМО, 1 grm. per litre. 
. Pelvetia (attached to stones). KNO; 1 grm. per litre. 
4, Pelvetia (cut off stones) laid on wool. Green light. 
5. Pelvetia (attached to stones), Green light. 
6 
7 
Ww № н 
. Pelvetia (cut off stones) laid on wool. 
. Pelvetia (loose) laid over pebbles. 
8. Pelvetia (attached to stones) laid on wool. 
9. Pelvetia (attached to stones) check. 
Two other cultures were made in which the tides were reversed, i. e. the 
plants were under water when the rest were dry, putting them in effect in a 
position on the beach just below the low-water mark of the neap-tides :— 
10. Fucus (from marsh) over pebbles. 
11. Pelvetia (attached to pebbles). 
Remarks on the Cultures.—The original idea was to see whether there was a 
necessary connection between the attachment of the alga and its fruiting ; 
but as, after six weeks, none of the cultures showed any signs of producing 
receptacles, they were discontinued. It may be that the plants can be 
induced to fruit by a more careful choice of conditions, but at present the 
results are negative. In spite of this, however, one or two points can be 
gathered from the cultures. 
The experiments were begun on July 24, 1910. On August 24 culture 11 
(Pelvetia below the low-water mark of the neap-tide) was obviously quite dead, 
having been apparently almost lifeless for about a week ; none of the other 
cultures were dead. On Sept. 7, none of the other cultures were dead. ‘This 
shows that Pelvetia, unlike the Fuci investigated earlier *, will not grow 
under the tidal conditions obtaining on the lower part of the shore. The 
reason of its confinement to the upper parts of the beach is, that it will not 
tolerate too long an exposure to sea-water. 
A second point to be noted is that in culture no. 2 (Pelvetia from stones 
lying on a surface constantly charged with КМО, solution) there was, at the 
end of the time, Sept. 7, a decided tendency to curl at the ends of the fronds ; 
also, of thirteen plants, three had produced vegetative buds. The curling was 
very slight compared with that of the loose form of Pelvetia, but it was not 
observable in any of the other cultures. No change was apparent in the 
form of either the loose Pelvetia ог Fucus after the treatment. Тһе curling 
of the thallus observed in culture 2, where it was in contact with a surface 
constantly charged with nutrient salts, may be something akin to what has 
happened on the marsh, where a stray plant with such a curling tendency 
would soon become entangled in the vegetation and form the nucleus for 
* ‘New Phytologist,’ vol. viii. p. 201. 
