STRUCTURE.] 



INTEGUMENTS OF THE SEED. 



27 



testa, and by many is considered a portion of the outer 

 integument, which is the most accurate mode of under- 

 standing it. 



172 175 178 184 183 186 



182 



172. Seed of a Garden Bean. 173. The same, after germination has just begun, and the testa 

 is thrown off. 174. Fruit of Mirabilis Jalapa, with the embryo commencing the act of ger- 

 mination by protruding the radicle. 175. The same, disentangled from the pericarp, and 

 become a young plant. 176. A section of the seed of Sterculia, with the embryo inverted in 

 the midst of albumen. 177. The embryo of Pinus, taken out of the seed, to show its nume- 

 rous cotyledons. 178. The same, after germination has advanced a little. 179. Seed of 

 < ).\alis, with the revolute elastic epidermis of the testa. 180. Seed of Salsolaradiata divided 

 vertically, and showing the annular dicotyledonous embryo, rolled round the albumen. 181. 

 Embryo of the same, taken out of the seed. 182. Section of the seed of Cyclamen, showing 

 the t.ansverse embryo lying in the midst of albumen. 183. Section of the fruit of j& Grass, 

 with the lateral embryo at the base. 184. The same, with germination just beginning. 

 185. The same, after germination is completed, and the monocotyledonous embryo become a 

 young plant. 186. Section of seed of Scirpus, with germination begun ; the solitary coty- 

 ledon is retained within the testa, the plumule and radicle are growing beyond it. 187. Section 

 of a Grass seed germinating ; the plumula is directed upwards like a slender horn ; the 

 cotyledon is at its base, adhering to the albumen. 188. Seed of Commelina germinating ; 

 the cauliculus is protruded, is emitting radicles from its end, and has pushed aside the lid 

 called embryotega. 



According to Schleiden, the integuments of the seed expe- 

 rience many changes during the period of ripening, so that 

 their original number can rarely be recognised. They are 

 sometimes all consolidated so as to form but one ; or they are 

 broken up into many layers, having no relation to the original 

 number of integuments. In Menyanthes, which has but one 

 integument of the ovule, the seed appears to have two, because 

 of the separation and lignification of the epidermis of that 

 integument ; and in Canna there are five layers of tissue 

 resembling integuments, although the ovule has not even one 

 complete integument. In the case of Spurgeworts, Rock Roses 

 (Cistacese) and Daphnads, a peculiar process takes place ; 



