THE TREATMENT OF LEAVES 203 



epidermal or (in older leaves) from the subepidermal cells, 

 their appearance being preceded by the development of a 

 certain amount of true callus, the outermost cells of which 

 are the actively dividing ones. When the small tubercle of 

 callus tissue has attained a certain size, then a ring-like pro- 

 tuberance makes its appearance, which grows up in the form 

 of a sheath round the apex and forms the first leaf or scale of 

 the young bulb. 



The formation of these small bulbs (hidbils) is best seen in 

 the case of Lilmm auratum or tigrinum. Here they make 

 their appearance on the inner surface of the leaf near the 

 margin, while the roots arise from the bast region of the 

 fibro-vascular bundle. The latter are, however, only of very 

 short duration, as the new bulbs very soon form their own 

 roots. 



In most cases, however, it is not necessary to stimulate 

 the leaf to the formation of buds by wounding it, as the 

 leaves will readily form buds of their own accord. This 

 voluntary formation of buds is not in any way different from 

 the bud formation of cuttings. Examples of it may be 

 found in the groups of Mosses and Ferns, as well as among 

 the Lilies in the group of Monocotyledons. It occurs 

 frequently, too, among Dicotyledons, where the buds are 

 generally formed in the axils of the veins, and are larger 

 and stronger the larger the vascular bundle is next which 

 they lie. 



It is very well known that the leaves of Bryophyllum 

 calycinum produce such buds in the depressions between 

 the teeth of the leaf, where a meristematic tissue occurs, 

 which soon begins to form buds. 



As such buds, when carefully removed, may readily be 

 grown into separate plants, the knowledge of plants pro- 

 ducing such bulbils is useful to gardeners. We will, there- 

 fore, give a list of plants in which they will be found to 

 occur: — Hyacinthus Fauzolsii, Fritillaria impericdis, Ather- 

 urus ternatus, Ornilhogalum thyrsoidrs, Drimia, Malaxis, 

 Cardamine, Nasturtium, Tellima, Siegcshcckia, Utricularia, 

 Calanclioe, Begonia quadricolor and phyllomaniaca, Nymplima, 

 micrantha (according to Caspary), and its hybrids. If the 



