44 THE BOOK OF NATURE STUDY 



surface is smooth, but the upper surface is studded with an enormous 

 number of small glands. These are of two kinds, as can just be 

 seen with a good lens, though microscopical study is needed to 

 show their structure. Some of the glands are on the surface of 

 the leaf, while others are raised on a stalk-like cell. These glands 

 secrete a sticky mucilage, as can be shown by touching the upper 

 surface of the leaf. It is easy to withdraw the finger from the leaf, 

 but when a small midge or other insect lights or crawls on the 

 leaf it is held fast by the sticky secretion and dies. Leaves may 

 often be found studded over with the insects thus captured. The 



presence of the insects (or of small 

 pieces of meat or egg placed experi- 

 mentally on a leaf) causes the edges 

 of the leaf to roll in somewhat and 

 the glands to pour out a digestive 

 secretion, which, as in the Sundew, 

 renders the substance of the animal 

 soluble. This is then absorbed into 

 the plant by the leaf. The digestive 

 secretion is only poured out when 

 the substances placed on the leaf 

 are of a meat-like or albuminous 

 FIG. i2.-piant of the Common Butter- nature. The plant, as in the case of 

 wort in flower. (After Baiiion.) the Sundew, can live without insect 



food. Its leaves are green and it can 



manufacture food like any ordinary green plant, though it doubt- 

 less benefits by the addition to its food supply that it is specially 

 adapted to obtain. 



Slender leafless branches, each of which bears a single large blue 

 flower, stand in the axils of the foliage-leaves. The structure of 

 the irregular flower will be understood from Fig. 13 with the aid of 

 a brief description. There is a calyx of five small sepals. Within 

 this comes the large irregular corolla, composed of five united 

 petals. The lower portion of the corolla is continued back as a 

 long pointed spur, in which the nectar is contained. The two 

 very short stamens are attached to the anterior side of the corolla 

 near its base, and their anthers face downwards. The globular 

 green ovary surmounted by a short style and a two-lobed stigma 



