CH. Ill] ROOTS. 73 



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

 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 on 

 the glands of separate tentacles : the feeding may be 

 repeated every four or five days. The plants should be 

 gro^\Ti under wooden frames covered with fine netting (mesh 

 1*5 mm.) to exclude insects. The fed plants soon begin to 

 look clearly greener and more vigorous than the unfed 

 ones. To get a good result the experiment should be 

 begun in May or June and continued to the middle of 

 August. The number and height of the flower scapes, 

 the number and weight of capsules, the number of seeds 

 per capsule, &c. should be compared. Or the plants may 

 be carefully washed and dissected out of the moss and the 

 dry weight per plant of the fed and starved specimens 

 compared. 



Section C. Roots. 



(87) De Saussures experiment^. 



When plants are placed in solutions of various salts 

 they do not, except under certain conditions, absorb the 

 water and salt in the same proportion. De Saussure, 

 using solutions that were not very dilute, found that the 

 plant absorbed relatively less salt than might have been 



1 De Saussure, Recherches chimiques, 1804, p. 247. 



