CONCERNING BULBS xiii 



that of the tulip, consist of overlapping scales, but of a 

 more or less homogeneous mass enclosed in a stiff 

 membrane, within which may sometimes be seen two or 

 three smaller membranes of similar structure. From the 

 lower part of the " bulb " issue roots, and from its summit 

 proceed the leaf-bearing and flower-bearing shoots. The 

 crocus "bulb" is not strictly what botanists call a bulb, 

 but is a corm (Ko/oyuo? = a stem), the expansion being 

 composed of the swollen base of the stem and not, as 

 with true bulbs, of the leaves the latter having de- 

 generated into mere membranous sheaths, which have no 

 function beyond serving as protective envelopes for the 

 food store and living nucleus within. As in the case of 

 the tulip, so the crocus, having flowered in the early days 

 of the year, proceeds to make and store up fresh supplies 

 of starch and other food in readiness for the following 

 year. The base of the stem enlarges above the old and 

 withering corm, from which it sucks the remaining 

 nutriment. Fresh roots are formed, some of which, 

 having penetrated the soil to a varying depth, contract in 

 length, and so draw down the new corm to the level of 

 the old. 



This contractile power of roots has another office of 

 great interest in connection with bulbs and corms. I 

 have said that new bulbs form around the old exhausted 

 ones by the development of buds in the axils of the leaf 

 scales. It is obvious that in this way overcrowding 

 must result, and that the young bulbs must often fare 

 badly through being obliged to seek nourishment from 

 soil already half exhausted of the elements necessary for 

 the plants' health. But by the development of lateral 

 roots which subsequently contract, such bulbs are often 

 pulled to an appreciable distance from their parent, and 

 thus gradually by yearly steps spread over a considerable 

 area. Kerner|quotes an interesting illustration of this 

 process. Some*soil containing bulbs of Tulipa sylvestris 



