W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 257 



germination of Ruppia, has already drawn particular notice to 

 the fact, that the germination not only of Potamogeton, but of 

 all the grasses in which the first leaf stands before the scutellum, 

 agrees in the main points with that of Zostera. The history of 

 development of these embryos, far from weakening the founda- 

 tion for such an interpretation of the individual parts, rather 

 speaks more distinctly in favour of the so-called scutellum of the 

 embryos ofZea and Sorghum being analogous to the first, leafless 

 axis of Zostera^. 



The course of development of the embryo of other Mono- 

 cotyledons, so far as known, gives still further probability to the 

 idea that the "cotyledon^^ is an axis with limited growth, from 

 the side of which breaks forth a sprout, the future leaf-bearing 

 main axis of the plant. I refer to the history of development of 

 the embryo of Cannaf given by Jussieu, with which completely 

 agree, besides those of the plants mentioned by Jussieu himself, 

 those of Hyacinthus comosus, Funkia ccerulea, Fritillaria impe- 

 rialis and other Liliaceae, that of Iris and others. In all cases 

 the first cell of the embryo (the lowest cell of the pro-embryo 

 forming the suspensor) becomes converted by a series of divisions 

 into a globular, ovate or spindle-shaped cellular body, the in- 

 crease of thickness of which is arrested at a point below the 

 summit. Thus is formed a lateral, more or less deep slit, from 

 the bottom of which is developed the plumule, in one case {Fri- 

 tillaria) not till after germination. No fact is less available as 

 testimony against the axial nature of the so-called cotyledon of 

 the Monocotyledons, than that of its base enclosing the plumule 

 as a sheath. If the secondaiy axis originates at a point on the 

 primary in which the growth in thickness of this latter is arrested 

 some time before the appearance of the lateral sprout, the en- 

 compassing of the new axis by the thickened borders of the 



* See figures ] 2-1 4, 32-34 of PI. xi. of my Essay Die Enstehung des Embryo 

 der Phanerogamen. At the time when I published those researches, not yet 

 enlightened by the study of the formation of the embryo of the Naiadeae, I 

 thought myself obliged to adhere to the view advocated by Bernhardi, Schleiden 

 and Jussieu, although it did no little violence to the phaenomena observed. The 

 papilla of cellular tissue becoming the plumule, appears from the first distinctly 

 lateral and below the apex of the nascent ** cotyledon," in these grasses, as also 

 in the Avenacece and TriticeeB. 



t Loc. cit. p. 348. 

 SCIEN. MEM.— A^a<. Hist. Vol. I. Part III. l7 



