x] CYMODOCEA AND ZOSTERA 127 



filled by the embryo with its enlarged hypocotyl, enclosed in 

 a brown membrane. As the fruits develop, mature, and 

 become detached, while still buried in the soil, there is no 

 chance of their becoming disseminated, unless tempests or other 

 accidental causes stir up the sea bottom ; this explains the rarity 

 of their occurrence among shore debris. Bornet several times 

 found branches bearing two or three generations of fruits. 



An Australian species of the same genus, Cymodoceaantarctica, 

 Endl., exhibits an interesting variant on C. aequorea in the 

 matter of the fruit 1 . The plant is annual, or at most biennial, 

 and the germination is viviparous. When the seedling attains 

 a length of 3 to 4 inches, it breaks away from the parent, but 

 carries with it a cup-like body (? the remains of the ovary wall) 

 which has been described as bearing " two unsymmetrical pairs 

 of basket-like spines." The " cup," on account of its relative 

 density, "retains the floating waif in an upright position, and 

 soon proves its ultimate use by acting as a grappling apparatus, 

 catching in the tangles of small algae etc." The young ^pfents' 

 develop spirally twisted roots, which presumably also serve for 

 anchorage 2 . 



In Zostera marina^ L., the Grass-wrack of our shores, the 

 fertile and sterile plants are readily distinguishable from one 

 another, since in the fertile plant the stem is slender, erect, and 

 much branched, while that of the sterile individual is thick, 

 creeping, more luxuriantly leafy, and anchored to the soil by 

 adventitious roots developed in bundles beneath each leaf base 3 . 

 Figs. 85 and 86, p. 128, illustrate the leaf anatomy. The inflo- 

 rescence, unlike that of Cymodocea, consists of a number of male 

 and female flowers, reduced to stamens and carpels and enclosed 

 in a spathe. A French observer 4 has given a vivid description 

 of a successful attempt to observe the actual pollination. Having 

 found a good locality for the purpose, in the month of June, 

 1872, in his own words, "j'allai m'installer avec mon micro- 



1 Tepper, J. G. O. (1882) and Osborn, T. G. B. (1914). 



2 See p. 205. 3 Gronland, J. (1851). 4 Clavaud, A. (1878). 



