AiYGIOSPENMS : SEED. 333 



within the <i\'ule and the .s^TDWth "f the endusperm is takin,c^ 

 place, where this is feinned, other correlated changes occur in 

 the outer parts of the ovule, and often in adjacent parts of the 

 flower. These unite in makini,'- the " seed, " or the " fruit. " 

 Especially in connection with the formation of the seed a new 

 growth of the outer coat, i ir integument, of the ovule occurs, 

 forming the outer coat of the seed, km^Mi as the les/j. while 

 the inner integument is absorbed. In some cases the inner 

 integument of the ovule also forms a new griiwth, making an 

 inner ciat of the seed (rosacea). In still r.ther cases neither 

 of the integuments develops intij a testa, and the embryo sac 

 lies in contact with the wall of the ovary. Again an additional 

 envelope grows up around the seed: an example of this is 

 found in the case of the red lierries of the " yew " (taxus), the 

 red outer coat being an extra growth, called an aril. 



In the willow and the milkweed an aril is developed in the 

 ftirm of a tuft of hairs. (In the willow it is an outgrowth of 

 the funicle, = stalk of the o\"uIe, and is called a funicular aril; 

 wdiile in the milkweed it is an outgrowth of the micropvle, = 

 the open end of the o\'ule, and is called a micropylar aril.) 



664. Increase in size during seed formation. — Accompany- 

 ing this extra growth of the different parts of the ovule in the 

 formation of the seed is an increase in the size, so that the seed 

 IS often much greater in size than the ovule at the time of fer- 

 tilization. At the same time piarts of the ovary, and in many 

 plants, the adherent parts of the floral en\elopes, as in the apple; 

 or of the receptacle, as in the strawberry; or in the involucre, 

 as in the acorn ; are also stimulated to additional gTowth, and ^ 

 assist in making the fruit. 



