SECT. II. APPENDAGES OF THE FRUIT. 18Q 



of integuments common to seeds in general, and 

 are consequently not essential to the idea of a seed. 

 The following different species are generally enu- 

 merated by botanists : the pellicle, the aril, the 

 down, the tuft, the tail, the beak, the wing. 



The pellicle, or seminal epidermis of Gasrtner, The pel- 

 is a fine and transparent membrane, investing and 

 concealing the proper surface of the seed, and ap- 

 parently so identified with its substance, as to be 

 not very easily discovered. It is exemplified in 

 the seeds of Salvia and Convolvulus, in which 

 last it is said to be covered with a sort of down.* 

 Its adherence to the seed is so complete that it 

 never separates spontaneously from it, but may be 

 detached from it by putting it into water, in which 

 it becomes mucilaginous. The same effect takes 

 place also in the process of germination, as may be 

 seen in the case of the germinating seed of the 

 Fir, or, perhaps, of any other seed furnished with 

 the pellicle in question. 



The aril is a tunic or coat formed by an expan- The aril, 

 sion of the umbilical cord, and proper to an in- 

 dividual seed, which it invests either wholly or in 

 part, though not adhering to it closely except by 

 the base, and detaching itself at last spontaneously. 

 It is elegantly exemplified in the outer and orange- 

 coloured coat of the seed of Evonymus europaus, 

 that presents itself so conspicuously to the eye 

 when the valves of the capsule have opened. In 

 * Smith's Introduction p. 296. 



