^38 



Germination 

 «f grasses. 



Amphibious 

 tDammaliar* 



ftCJEKTlIXC K£W5l. 



observes hav^e 3 doui^le . ori^anization, relating, en the c^fe 

 hand, to the earth, in which thej spread thtir roots; on the 

 other, to the air, in Ahicfi their leaves are expanded; The 

 roots are destiued to the ascending vegetation ; the leaves, 

 to the descending ; and it is at the point where these two 

 •ysteras unite, that the cotyledons are usually placed. But 

 the lobes of the nelumbium are at the lowest part of the 

 plant, and consequently belong to the roots. The example 

 of many other plants destitute of cotyledons shows, that 

 they are not essential to vegetation ; and that the characters 

 derived from them to arrange thfe vegetable kingdom in 

 three divisions are insufficient^ and should be replaced by 

 those arising from the direction of the vessels and medullary 

 radii. 



Mr. Poiteau has examined the germination of grasses. 

 The part of the seed, wiiich ought to be considered as the 

 cotyledon, is yet questioned among botanists. Mr. P., ob- 

 serving that the scutum, which Giiertner took for a vitellus, 

 and Mr. Richard for the body of the radicle, was placed at 

 the point where the plumula and radicle separate, deems 

 this a true cotyledon. Mr, P. has observed too, that, the 

 moment when the' radicle of a grass is unfolded, it assumes 

 the iigure of a cone, and represents the taproot of other 

 plants ; but as soon as the lateral roots have acquired a cer- 

 tain growth, this cone is obliterated, so that no plant of this 

 family has a taproot. And as Mr. P. has made the same 

 observation on several other monocotyledons, this substitu- 

 tion of numerous secondary roots for ope principal root 

 takes place,- because each bundle of fibres of the monocoty- 

 ledons has its peculiar root. . . > 



The researches of Mr. Cuvier cQi^cerning fossil animals 

 have commonly led him to discussion^ respecting the spe- 

 cies admitted by naturalists, tending generally to the ad- 

 vancemfcut of the science of zoology. Thus in considering 

 the organization of the amphibious mammalise, he has been 

 led to separate from the seals and morses, the Indian wall- 

 rus, the manatees, and the species described by Steller. 

 These three genera form one family, distinguished by the 

 absence of the posterior extremities, and by herbivorous 

 teeth. 



In 



