414 William Russel Dudley 



tioii of the stem of Ph. Scouleri. The stem and the leaf we 

 have found bear the brunt of the surf; and underneath the 

 thick chlorophyllous epidermis, destitute of stomates, both 

 members show large areas of strong sclerenchyma fibres (so.), 

 each fibre several millimeters long and of surprising strength. 

 In the flat leaf of Ph. Scouleri, the entire margin of the leaf 

 beneath the epidermis is a steel}^ strand of sclerenchyma, and 

 the remaining tissues are well armored with it. Schwenden- 

 er's demonstration in "Das Mechanische Princip," that the 

 sclerenchyma is the prime factor in the strengthening appara- 

 tus of a plant could find no better illustration. For after the 

 old leaves are beaten to pieces b}^ the tremendous surf these 

 fibres long remain at the base. Bold shore specimens can be 

 recognized in herbaria from the numerous bristle-like strands 

 of sclerenchyma remaining at the base of the stems. 



The longi- and transections under M, of a stem fibro- vascular 

 bundle, illustrates its simple and feeble structure. 



Zostera leaves, even those of our large coast species, show 

 large lacunae and no sclerenchyma fibres whatever, in the 

 specimens examined. The stems are relatively no stronger. 

 These Monterey Bay Zosteras, although in open water are 

 subjected to no such impact as the plants growing in the surf. 

 It is only in the rhizoma, where there are scattered strands of 

 sclerenchyma, that we find a member stronger than in Phyl- 

 lospadix, the roots being without strengthening elements, as 

 Sauvaugeau has demonstrated those of Zostera marina to be. 



Aside from correcting certain errors this structural study has 

 brought out two salient facts : First, the genus Phyllospadix, 

 not 3'et found fossil, so far as we know, is probably an off- 

 shoot and apparently a recent one, from the much older genus. 

 The presence of the now quite useless but still well marked 

 rudimentary male organs on the pistillate spadix, which pre- 

 sent us with an inflorescence identical in plan with that of 

 Zostera, is offered as evidence of this ; while the separation of 

 the sexes, on male and female plants, indicates a differentia- 

 tion in advance of the original monoecious arrangement still 

 adhered to in the last-named genus, and shows the vigor of 



