8 
the plumule-sheath as belonging to the cotyledon, but in 1815 returned 
to his former view. Treviranus' opposed Richard’s view and regarded 
the scutellum as a cotyledon. He speaks of the scutellum as enlarging 
itself the length of the seed and taking on a yellowish color, which is 
certainly not the case. Turpin’ agreed with Mirbel that the embryo 
has two cotyledons. According to Cassini? the embryo of the grasses 
is composed of an axis, a cotyledon, one or two radicles, a plumule, and 
one or two *carnodes." His “cotyledon” is the plumule-sheath, while 
the “carnode,” a name for the scutellum, he regards as a protuberance 
of the radicle. Raspail! compared the fruit and the flower. He 
believed that there was also a homology between the embryo and the 
culm. On examining the cotyledon he discovered a large nerve, join- 
ing the two nerves of the plumule-sheath at the base. From this he 
concluded that the scutellum is homologous to the peduncle of the 
aborted flower in the spikelet and to the sheath of the culm-leaf. He 
compared the plumule-sheath with the two-nerved palet in the spikelet 
and to the first leaf of the vegetative bud, and the endosperm to the 
flowering glumes of the spikelet and to braets on the eulm. 
Dr. €. A. Agardh* in 1526 compared a longitudinal section of the 
embryo of Ruppia with the grass embryo and fruit, and found a great 
Similarity between them. He regarded the entire endosperm of the 
grasses as the cotyledon, and the scutellum as a covering of the same. 
This, however, is impossible, as the scutellum never surrounds the 
endosperm. Bernhardi* believed that a cotyledon must, aside from its 
function of nourishment, also aet as a protective organ to the young 
leaves. He therefore regarded the plumule-sheath as a cotyledonary- 
sheath and the scutellum as a cotyledon. Bischoff? also believed that 
the scutellum and epiblast are two cotyledons. He regarded the 
caryopsis as having an embryo with alterhate cotyledons, without how- 
ever giving any special grounds for this opinion. M. J. Schleiden“ 
was the first to study the develo»ment of the grass embryo. Accord- 
ing to him the seutellum and tle plumule-sheath together form the 
cotyledon. He regards the epiblast as an outgrowth of the cotyledon, 
since it is connected with the main axis lower down than the cotyledon 
ee e e e 
Te der Entwickelung des Embryo und seiner Umhilllungen ee Pflanzen Ek 
* Mémoire sur l'inflorescence des Graminées. Ann. d. Mus. d'hist. Nat, 1819. 
? L'analyse de l'embryon de Graminées, Jour. de Physique. T.91. 1820. 
4Sur la formation de l'embryon dans les Graminées. Ann. des Soc. Natur, Series 1, 
vol. 4, plates 13-14, 1824, 271-290. 1824. 
5 Uber die Eintheilung der Pflanzen mee m 5 und besonders über den 
Samen der Monocoty ledon nen. 1 Nov. B.G, 4 
Li M —— der merkwürdigsten 5 2. E as Pflanzenembryo. 
"Lehrbuch der Botanik I. 1834. 
Wieg. Archiv. II, L 1837. . des vegetale Organ bei den Phan., : 
