ISO VEGETABLE ORGANOGRAPHY. 



is inclined to confound them sometimes with parts of the 

 pericarp, at other times with those of the seed. 



The most simple cases are those where the funiculus 

 expands laterally, so as to form an appendage upon the 

 seed ; thus, in several Polygaleae, we find a lateral 

 arillus which evidently arises from the funiculus. In 

 this case, it is usually fleshy or membranous; it is, 

 perhaps, to this order of unilateral arilli, that the carun- 

 culi which are found in some species of Dolichos and in 

 Chelidonium ought to be referred. In the Nutmeg the 

 arillus is large, fleshy, and ramified, forming a kind of 

 incomplete envelope at the base of the seed ; it is what 

 is commonly called Mace : in Blighia it is so large and 

 •fleshy as to be worth the trouble of collecting for food. 

 The same phenomenon occurs in the Passifloreae, where 

 the inside of the arillary coat is full of a pulp secreted 

 apparently by the walls of the arillus ; when abundant, 

 it causes some capsules of the Passion-Flowers to be 

 classed with edible fruits. 



In all the examples which I have mentioned, the 

 arillus forms an incomplete envelope around the seed, 

 and this is what ought to be considered the distinctive 

 character of this kind of expansion of the funiculus. 



We give, on the contrary, with Gaertner, the name of 

 Epidermis, to a dry, thin, membranous sac which en- 

 tirely covers the seed ; this organ is very visible in the 

 Malvaceae, Bombaceae, &c. 



It is to be remarked that the arillus, whether it be 

 fleshy, membranous, or pulpy, never bears hairs ; on the 

 contrary, the epidermis is sometimes smooth, as in the 

 Gourd, but more frequently furnished with hairs ; and 

 as the skin of the seed, properly so called, never bears 

 hairs, whenever a seed appears so covered, it is because it 

 is invested with a very adherent hairy epidermis ; these 

 hairs are either very short, as in most Mallows, or very 



