232 THK VITBLLUS, Oil YOI.K. 



• 



as in the genus Zamia.f. 200, closely allied to the 

 latter, see his t. 3, and even in Ruppia^ Engl. Bot. t. 

 136, and Cyamus. In the natural oidcr ol" Grasses 

 the part under consideiation forms a scale between the 

 Embryo and the Albumen. 



I cannot but think that the true use of the Vitellus 

 may be to perform the functions of a Coiyled n wih 

 regard to air if not to light, till a real leaf can be sent 

 forth, and the " subterraneous Cotyledons" ofGoert- 

 nerin the Horse Chesnut and Garden Nasturtium are, 

 as he seems to indicate in his Introduction, p. 151, 

 rather of the nature of a Vitellus. It does not appear 

 that any plant with genuine ascending Cotyledons is 

 likewise furnished^ with this organ ; on the oth:."r 

 hand, it commonly belongs to such as have the most 

 copious Albumen^ and therefore should seem to answer 

 some other end than mere nutriment, which is suppli- 

 ed by the latter. 



We learn from the above inquiries, that the old dis- 

 tinction between plants with one CotyUdon and those 

 with several may still be relied on, though in the for- 

 mer the part which has commonly been so denomina- 

 ted is the Albumen, as in Corn, the real Cotyledon of 

 which is the scale or Vitellus, which last organ howev- 

 er seems wanting in Palms, Lilies, &c., such having 

 really no Cotyledon at all, nor any thing that can 

 perform its office, except the stalk of their Embryo.* 

 In the Horse Chesnut, Oak and Walnut possibly, 

 whose seed-lobes do not ascend, the functions of a 



* This may answer the purpose of a Cotyledon, just as the 

 3tems of many plants fulfil the office of leaves. 



