HAIRS AND THEIR USE 



Then on the Chickweed and the Bird's-eye Speedwell 

 there are lines of rather long, flexible hairs which at first 

 sight appear to be of no use at all. But if you take either 

 of these plants, and, holding it upright, place a large drop 

 of water on the leaves, you will see that these hairs are 

 intended to carry the water down the stem. The water runs 

 along them. It is a very pretty little experiment, especially 

 if done in artificial light, so that these hairs are, like the 

 root hairs, intended to absorb or suck up water as it passes 

 over them. Then the Edelweiss and the Lammie's Lug 

 {Stachys lanatd) are entirely covered with white cotton-woolly 

 hairs : these are intended to keep the water in the plant, 

 and do so as effectually as a rough woollen coat will keep 

 out rain and mist. Silky hairs, downy hairs, and others are 

 found wrapping up the tiny baby leaves in the bud: they 

 probably keep them warm, and perplex and ward off objec- 

 tionable insects. 



But, perhaps, the sticky or glutinous hairs are the most 

 wonderful of all. They are found on many plants, such as 

 Salvia glutinosa^ Plumbago, and Catchfly. One can see 

 insects stuck on them and vainly struggling to be free, and 

 the hairs undoubtedly prevent green-fly and other such pests 

 from interfering with the honey of the flower. In some of 

 these cases it has been shown that the body of the insect is 

 actually used as food, but that is more obvious with two 

 interesting plants which specially devote themselves to the 

 capture of insect prey. One of these is very often kept in 

 the Boer farmhouses near Tulbagh, in South Africa, simply 

 to attract the flies, which are a perfect pest in those dry 

 valleys. Another Drosophyllum, the Fly-Catcher, grows on 

 sandy and rocky ground in Portugal and Morocco. This is 

 ^ Macchiati, Botan. CentralblaU, 41, 190. 

 347 



