222 FORMATION OF PROTEINS 



material which may be sufficient to enable it to grow for' a long 

 time. 



The substances manufactured in a shoot or branch of a tree 

 are prevented from leaving it when the branch is ' ringed,' and 

 the shoot and fruits upon it grow more luxuriantly in consequence 

 of their increased food-supply. 



There is often a special growth of the wood and bast tissues 

 just above the ' ringed ' part in consequence of the accumulation 

 and utilisation of organic material at that point. 



Similar thickening or enlargement of the stem arising from 

 impeded flow of elaborated sap is seen immediately above the 

 point where scions have been inserted on stocks in the grafting 

 process, especially where the union of the two grafted parts is 

 imperfect. 



Wire or string tightly bound round the stems and branches of 

 trees leads to similar results. 



Ex. 129. — Remove leaves from tropseolum, clover, and other plants in the 

 afternoon and test for starch in them with iodine as in Ex. 123. Remove 

 from the same plants similar leaves in the early morning of next day and 

 test for starch. 



Compare the two sets of leaves and note the greater amount of starch in 

 those plucked in the evening 



Ex. 130. — Remove in spring or early summer a ring of bark about half an 

 inch wide from the branches of several kinds of trees. Also from some of 

 the branches remove two or three similar rings of bark near each other, so as 

 to leave a bud on some of the unringed portions and no buds on others. 



Note the subsequent growth and development of the various parts of the 

 shoots above and below the ' ring.' Do the buds lying between two ' rings ' 

 develop satisfactorily ? 



Ex. 131. — In spring before the leaf-buds are open make cuttings of the 

 willow about a foot long from well-ripened portions of last season's shoots : 

 'ring' the cuttings about one and a half inches from their base and place 

 some in water and others in damp soil. Leave them until adventitious roots 

 develop ; note the relative size and rate of development of the roots ard 

 . buds above and below the ' ringed ' part. 



Ex. 132, — Tightly bind string or wire twice or three times round the branch 

 of a tree, and observe the subsequent development of the various organs above 

 and below the bound part. 



