LECT. IX.] HYBERNACULA CAULINAR BULBS. 453 



it also acquires colour on that part of the surface 

 exposed to the light; passing first from white to 

 green,, then to light brown, and lastly to a very 

 deep shining jet brown. On attaining this degree 

 of maturity it separates from the stem on the 

 slightest touch, or it spontaneously loses its hold ; 

 and, dropping to the ground and vegetating, 

 throws out roots and acquires all the characters of 

 a root bulb. Linnaeus, nevertheless, regarded the 

 caulinar bulb as a gem, and denominated it Gem- 

 ma decidua* ; but, independent of its spontane- 

 ously separating from the parent, which the real 

 gem never does, it differs in other essential cha- 

 racters from the gem. 



Examining one of these bulbs in a mature 

 state, we find at its lower part a depression re- 

 sembling the hilum or scar, which on a seed 

 points out the place of its attachment in the seed- 

 vessel. It consists, in the bulb, of a depression 

 enclosing three elevated points, which indicate 

 the place where the vessels connecting it with the 

 parent entered. The bulb itself consists of two 

 outer scales, the uppermost large and embracing 

 the lowermost, which projecting forms the keel of 

 the bulb, and embraces another scale within it, 

 which in its turn embraces a fourth, and so on to 



* Species Gemmarum variae sunt, Deciduce in Dentaria, 

 Ornithogalo, Lilio, Saxifraga. Phil. Bot. 85. 



G G3 



