264 DECOMPOSITE ORGANS. CHAP. I. 



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evolution, but remain enclosed within the proper in- 

 teguments of the seed, and concealed under the sur- 

 face of the earth. They are exemplified in the 

 case of the Horse-chesnut and Walnut. 

 Acotyle- But although by far the greater number of seeds 



donous r . . . , . . 



seeds. are furnished with two cotyledons, or with a coty- 

 ledon visible or not divisible into several lobes, there 

 is also a considerable proportion in which the coty- 

 ledon is altogether wanting, or at least believed to be 

 wanting by botanists in general. These, according 

 to Gaertner, are exemplified in the Fuci, Ferns, and 

 Fungi, the embryo being merely a germinating 

 cicatricle imbedded in the surface of a vitellus 

 which forms the mass of the seed. 



But Hedwig, to whose opinions on this subject 

 much deference is also due, maintains that the seeds 

 of the plants in question are furnished with cotyle- 

 dons as well as those of other plants, and that no 

 seed whatever is without them. This is a case, how- 

 ever, in which the general opinion of botanists is 

 against him, as may be seen from the many systems 

 founded upon the presence, or absence, or number 

 of the cotyledons, and exemplified in that of the 

 great and justly celebrated Jussieu, whose primary 

 divisions are those of acotyledonous, monocotyle- 

 donous, and dicotyledonous plants, the polycotyle- 

 donous being, perhaps, thought to be too few in 

 number to constitute a separate division. It should 

 Be recollected, however, that the above divisions 

 were instituted at a time when the subject had not 



