ENALUS ACOROIDES. 
287 
about the point where the spiral begins (PI. XXIV., B, 2) 
one of them is already a little larger and also especially the 
air chambers around it. These have apparently a tendency 
to originate radially around the larger bundle. The stem, 
originally bisymmetrical like that of the male inflorescence, 
thus becomes more and more monosymmetrical. In the 
general structure of the female pedicel Enalus thus agrees 
with Vallisneria, according to the description and figure 
given by Muller (21, tab. III., fig. 23). If now the different 
structure of the two larger bundles is accompanied by a 
different increase in length obliquely to the axis of the 
v pedicel, the result must be a spiral twisting of the pedicel. 
; The differences in the anatomical structure at various 
stages appear in the different degrees of development of the 
mechanical elements before and after the pollination and 
fertilization. After the fertilization (PL XXIV., B. 3), the 
smaller peripheral bundles are all combined on their outer 
sides with groups of mechanical cells. The walls of these 
outer cells have become thickened, but are not at all 
lignified, staining violet with iodine-zinc-chloride and not at 
all with aniline chloride, or phloroglucin and hydrochloric 
acid. They thus consist exclusively of cellulose. This 
development of mechanical elements at an older stage in the 
female pedicel corresponds, of course, to the augmented 
demand for strength when the fruit ripens, and this the more 
as the currents in the sea where Enalus lives are often very 
strong. In the pedicel of the male inflorescence these 
mechanical elements never occur, as is commonly the case 
■ in diclinous phanerogams (c/. Grevillius, 11). 
I The remarkable increase of the hair-like emergences on 
the fruit after fertilization may also be regarded as an 
adaptation to protect the fruit from being broken off by the 
currents. Certainly they keep the fruit well anchored in 
the mud, where this plant commonly grows. This seems to 
be the case wherever this plant lives; it was so at Paumben 
and all around Jaffna, and Kurz (19) has made the same 
