270 
Notes . 
falling tide brings the weight of the embryo on to its point, until it 
has reached the position of the lower specimen in the figure. 
The success of this method depends upon the action of ripples of 
the water, but on an exposed shore the waves will merely throw the 
embryo about as any other floating stick. Suitably shaped and fairly 
numerous crevices in the rock are usually met with near high-tide 
mark, the surface of the flats lower down being smoother and its 
crevices too shallow, or filled in with hard sand. In short, the condi- 
tions requisite to planting are generally those suitable for the life of 
the adult trees, but, as in the case of other trees, those conditions are 
sometimes found where the embryo can never develop into the adult. 
Embryos are often planted too low down the shore (I have even met 
with one, bearing two unfolded leaves, at low tide in the sand of the 
boat channel of the reef on the open coast), but in this case they 
will be usually floated off again by succeeding tides. 
There are thus tivo adaptations of the mangrove, ensuring that, in 
the case of those trees which are growing in mud, too many embryos 
shall not be swept out to sea, and also that those which are so 
removed shall have a good chance of taking root in fresh localities. 
The mangrove has thus an effective means of dispersal, and it is 
probable that the juxtaposition of trees from different sources, whereby 
continued in-and-in fertilization is avoided, is just as important for 
them as for the great majority of living things. Furthermore, this 
adaptation for dispersal enables the embryos to be planted on surfaces 
to which the formerly known method is inapplicable. 
CYRIL CROSSLAND. 
Cambridge. 
EXPLOSIVE DISCHARGE OF ANTHEROZOIDS IN FEGA- 
TELL A CONIC A. — Fegatella ( Conocephalus ) conic a is one of the 
commonest liverworts in the neighbourhood of Leeds. It grows in 
great abundance in moist and shaded places, especially on stones 
beside streams. In the beginning of July a large supply of male 
plants was collected, bearing young antheridial receptacles, which, as 
is well known, are sessile in this genus, and have the form of oval 
cushions, each situated at the anterior end of one of the branches 
of the thallus. Most of these plants were put into shallow vessels, 
covered with sheets of glass, and set in a shaded place. After a few 
