CH. Ill] DROSERA. 65 



geously be changed every few days. Drosera cannot be 

 successfully cultivated in large towns. For the experi- 

 ments fresh young leaves having good drops of secretion 

 on their tentacles should be selected. From the white of 

 a hard-boiled egg cut cubes of which the side measures 

 about a millimeter in length : place two of such cubes on 

 each of several leaves, and at the same time put other 

 cubes on the wet moss to serve as a control. They should 

 be examined in 24 hours and again after a further interval 

 of 24 hours. It will be seen that the egg on the Drosera 

 shows a distinct rounding at the angles of the cubes, 

 which are afterwards converted into spheres surrounded 

 by zones of transparent fluid. Still later the spheres 

 generally disappear and nothing but a small quantity of 

 viscid fluid is left. 



(86) Drosera: benefit derived by feeding^. 



The plants are, as in exp. 85, to be grown in soup- 

 plates, each of which holds from 20 to 30 plants. Each 

 plate must be divided in two by a thin wooden partition, 

 this serves to mark off those plants which are to be fed 

 from those which are to receive no food. Roast meat is 

 cut across the grain into thin slices and the fibre teazed 

 and cut into fragments so small that 15 together weigh 

 2 centigrams. A given leaf should not receive more than 

 two of these particles at a time ; they may be placed pn 

 the glands of separate tentacles : the feeding may be 

 repeated every four or five days. The plants should be 



' F. Darwin, Linneau Society's Journal, vol. xvii. For references to 

 other similar experiments see Insectivorous Plants, 2nd Edit. 1888, p. 15. 



, D. A. 5 



