292 OF THE VITELLUS, 



Vitellus, the Yolk, first named and fully 

 illustrated by Gaertner, is less general than 

 any of the parts already mentioned. He 

 characterizes it as very firmly and insepa- 

 rably connected with the Embryo, yet 

 never rising out of the integuments of the 

 seed in germination, but absorbed, like 

 the Albumen, for the nourishment of the 

 Embryo. If the Albumen be present, the 

 Vitellus is always situated between it and 

 the Embryo, and yet is constantly distinct 

 from the former. The Vitellus is esteemed 

 by Gaertner to compose the bulk of the 

 seed in Fuci, Mosses and Ferns, as well as 

 in the genus Zamia, closely allied to the 

 latter, see his t. 3, and even in Ruppia, 

 Engl. Bot. t. 156, and Cyamus. In the 

 natural order of Grasses the part under con- 

 sideration forms a scale between the Mm- 

 bryo and the Albumen. 



I cannot but think that the true use of 

 the Vitellus may be to perform the func- 

 tions of a Cotyledon with regard to air if 

 not to light, till a real leaf can be sent 

 forth, and that the " subterraneous Coty- 

 ledons" of Gaertner in the Horse Chesnut 



