T.IFK OF TLA NTS. <;>59 



part of the knot, and rises from thence into the plant. We 

 thus perceive, that in plants of the higher kinds, the cotyle- 

 dons are a necessary instrument of germination and growth ; 

 on which account, when both the cotyledons are cut off, t he- 

 plant of necessity dies. 



386. 



The distinction which has been made, chiefly since the 

 lime of Ray, between the Acotyledonous, Monocotylcdonous, 

 Dicotyledonous, and Polycotyledonous plants, — a distinction 

 which still prevails in the system of Jussieu, — entirely vanishes 

 upon a more exact and more general observation of nature. 



Among the Acotyledonous plants were mentioned the Fun- 

 gi, Algae, Lichens, Homallophyllae, Musci hepatici and fron- 

 dosi, Ferns, and Naiada?. But it has been already shewn 

 (30^, 307.), that Fungi, Alga?, and Lichens, are propagated 

 l)y germs only ; and that Homallophylla?, Musci hepatici and 

 frondosi, and Ferns, during gennination, produce fluctuating 

 fonns, which might be regarded as representatives of the co- 

 tyledons. In the Naiadas, the thickened cotyledonous end of 

 the root renders, in most instances, the cotyledons superfluous, 

 and in some cases the albuminous substance, {Zostcra, Riip- 

 pia^ Zannichellia^ Potamogeton.) \\\ other Naiada? {Lemna, 

 Hipptirls), the embryon is entirely unevolved in the middle 

 of the albuminous substance ; and in others (CaUifriche, Ce- 

 ratophyllum, Myriophyllum), the embryon evitlently divides 

 itself into two cotyledons. 



With respect to what are called Monocotylcdonous plants, 

 Jussieu has reckoned them in this order, the Aroida^ Cy}3e- 

 roidae. Grasses, Palma?, Restiaceae, Juncea^, Sarmentaccjv, 

 Coronariae, Irideae, Hydrocharidae, Scitaminea», IMusejc, Or- 

 chideae, and Pipereae. But in none of these plants can we 

 admit the existence of a proper cotyledon. Lidced, iMirbel 

 (Annal. du Mus.), Fischer (Ueber die Existen/ der Mono- 

 und Polycotyledonen), Smith (Linn. Trans.), and Trevira- 

 nus (Entwickelung des Eyes), consider the vitellus in the 

 Scitamineae, or the bodies resembling scutella in the Grasses, 

 as cotyledons; because there is a distinct tr?nisiti(.n U:a\\ 



\{ 'I 



