270 MANUAL OF BOTANY 



namely: — 1. The true arillus, as in Nymjihrsa {fig. 583, A, a) : 



2. The arillode or micropylar arillus, a.s in Euonijmus {fig. 584:) ; 



3. The rapliian arillus, a.s in Asarum (fig. 586) ; and 4. Tlie 

 chalazal arillus, as in Epilobium {fig. 587), where the tuft of 

 hairs at one end, of the seed is regarded as an aril. Other 

 writers again partially adopt these views, and define the carun- 

 cules as little protuberances growing from the raphe, and 

 therefore originating independently of the funiculus or micro- 

 pyle; hence the caruncules of Milkwort and Spurge would be 

 regarded as true or false arils according to their respective origins, 

 and the appendages of Asarabacca and Violet would be true 

 caruncules. Other botanists again, instead of using the two terms 

 strophioles and caruncules as synonymous with each other, apply 

 the former term only to the processes proceeding from the hilum, 

 and the latter to those coming from the micropyle. Altogether, 

 there is a great difference of opinion among botanists as to the 

 application of the terms caruncule and strophiole. 



2. The Kernel. — We have seen that the substance of 

 the seed is morphologically very complex in its nature. We 

 may or may not have the substance of the nucellus or part 

 of it remaining. Generally this is all absorbed during the 

 growth of the megaspore. In the seed, when present, it has 

 received the name of the 2}erisperm. We have next the emlryo- 

 sao or megaspore. In this there may be a solid mass of 

 tissue, known as the endosjperm, being part of the gametophyte. 

 Embedded in the endosperm is the body produced by the develop- 

 ment of the fertilised oosphere, which is called the enihnjo. 

 In other cases the embryo, by absorbing the nourishment con- 

 tained in the endosperm, obliterates the latter and comes to 

 occupy the whole interior of the embryo-sac. Then the kernel 

 of the seed consists of the embryo or young sporophyte, which 

 m rare cases is surrounded by a layer of perisperm, but is gene- 

 rally only covered by the integuments. 



To the tissue which thus sometimes remains and forms a 

 solid inass round the embryo, the name of albumen has been 

 commonly applied ; but it is preferably designated as the peri- 

 sperm or endospienn, according to its origin as described above. 

 Both endos2>erm, and perisperm may be seen in NijinphcBa {figs. 

 583 and 588). 



From the above considerations it will be evident that the 

 kernel of the seed may either consist of the embryo alone, as 

 in the Bean and Pea {fig. 611) ; or of the embryo enclosed in 

 endosperm, as in the Poppy (fig. 601), Pansy {fig. 600, al), Oat 



