72 DROSERA. [CH. Ill 



under the eye-piece micrometer, and cover the whole with 

 a darkened bell-jar. Examine the preparation from time 

 to time, and note the stages of germination. Measure the 

 germinal filaments, mycelial branches &c., and plot out 

 the rate of growth on sectional paper. 



(85) Drosera: digestion of ivliite of egg^. 



Drosera may be grown in wet moss in soup-plates : the 

 moss should be running with water which may advanta- 

 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 : i3lace 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 Qgg 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 



^ C. Darwin, Insectivorous Plants, p. 93. 



- F. Darwin, Unnean Society^s Journal, Vol. xvii. For references to 

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



