7i8 



MECHANICAL LAWS OF GROWTH. 



resistance of the wood has greatly increased ; were the pith now as elastic as before, 

 it would expand more rapidly when freed from the very great resistance of the wood. 

 The following table will now be understood ; the length of the entire internode 

 being always placed at loo, and the amount of contraction indicated by negative, of 

 expansion by positive percentages. 



Number of the internode, 

 countino; from the youngest. 



Change of length of the isolated tissue 

 in percentage of the entire internode. 



NicofiiVia Tahncum 



do. 



Sambuciis nigra 



do. 



do. 



These numbers, taken from my Handbook of Experimental Physiology, may be 

 supplemented by some others, calculated from the statements of Kraus^ (/. c. 

 Table i). 



Number of the inter- 

 node, counting from the 

 youngest. 



Change of length of the isolated tissue 

 in percentage of the entire internode. 



tensions may still continue. It must however be remarked that the method by which these num- 

 bers have been obtained is liable to considerable suspicion. 



^ Kraus has only given the absolute numbers ; but a correct notion can be obtained only by 

 comparing them with the length of the internode. 



