96 



DEVELOPMENT OF ALLIUM URSINUM. 



flowering specimens. The cotyledon and sheath, as well as the 

 lamina of the leaf, soon die and vanish. 



Tulipa Gesneriana, L. (Garden Tulip.) 



When a fertile bulb is examined towards the end of autumn, 

 the following appearances are presented. It is generally sur- 

 rounded by a thin brown skin, on the removal of which the dry 

 brown peduncle of the past season appears, furnished at its base 

 with the withered roots (Fig. 1, a). Between it and the fresh 

 bulb a thin dry brown skin (b) is found, which is frequently 

 lacerated both at its base and at the upper margin. This is 

 clothed with long shining hairs on its inner surface, especially at 

 the base, where it is connected with that of the dry peduncle. 



At the base of the new bulb on the side which is turned away 

 from the old flower-stem, the first rudiments of the roots appear 

 in the shape of little swellings disposed in a semicircle, whose 

 open side is towards the stem. In most species of Allium the 

 roots form a circle on the bulb. 



The fresh bulb is commonly formed of four (Fig. 2, c), or 

 more rarely of five, fleshy sheaths, with a rather narrow orifice. 

 They are disposed spirally, the innermost being the shortest. 

 In the axil of the inmost sheath which incloses the base of the 

 flower-stem (g) is situated the minute new principal bulb (Fig. 2, h), 

 the back of whose outer leaf is next to the flower-stem. In a 

 vertical section through all the parts of the bulb we see that the 

 young roots (Fig. 2, i) are formed on the same side as that on 

 which the young bulb is seated, and that this is on the side of the 

 fresh flower-stem which is turned away from the dried peduncle 

 (a) of the former year. Therefore, as in Gagea lutea, each succes- 

 sive plant is behind that of the previous season. The evolution of 



