STRUCTURAL AND PHYSIOLOGICAL BOTANY. 



537. Sometimes there are tumours of the testa near the 

 hilum or at the opposite end ; such are called StropMolte or 

 Caruncula . 



538. The precise nature of these is unknown ; sometimes 

 they are dilatations of the chalaza ; Ex. Crocus : or they are 

 caused by a fungous state of the lips of the foramen ; Ex. 

 Eicinus : or they arise from unknown causes. 



539. The scar, which indicates the union of the seed with 

 the placenta, is called the hilum or umbilicus 3 . 



540. The integuments are called collectively testa, and 

 consist of membranes resulting from the sacs of the ovule 

 (451). 



541. Sometimes the testa is covered by hair-like expan- 

 sions of its whole surface ; as in the Cotton : or these hairs 

 occupy one or both ends, when they constitute what is called 

 the coma' 287 . This must not be confounded with pappus (328), 

 which is calyx. 



542. The integuments are often expanded into wings, 

 which are either single 284 or several 277 , and appear intended 

 to render seeds buoyant. Very often they are corky or 

 spongy 282 , and not unfrequently consist of spiral cells (19). 



543. In the seed these membranes are called by various 

 names, of whiph the most frequently used are spermoderm or 

 testa for the primine ; mesosperm, for the secundine ; and endo- 

 pleura for the coat of the nucleus (450). 



