328 



Unless you are prepared to use it for the advancement of 

 knowledge, what does it profit you ? and unless by previous 

 study you are prepared to understand what you see, what 

 does it profit you ? 



I recognize the man of learning here, 

 What you touch not, lies not within your sphere ; 

 What you grasp not, does not exist for you ; 

 What you count not, most surely is not true ; 

 What you weigh not, devoid of weight you call ; 

 What you coin not, won't pass with you at all. 



"With these thoughts in mind, I have, as occasion offered 

 endeavoured to sketch out for you a plan of work to be done 

 in connexion with the Vegetable Kingdom. How small a 

 proportion this bears to the corresponding work required for 

 the animal world, I need not mention ; this I leave to my 

 successors ; it is for you to fill in the details. Having then, 

 put before you some of the leading features in the structure 

 of plants, perhaps on the last occasion when it will be my 

 privilege to address you, I may not unprofitably occupy your 

 time with a few supplementary remarks on the function of 

 the various organs — that is, the Physiology of Plants. 



We have seen that the first element in the formation of a 

 plant is a cell, originating from the combination of carbonic 

 acid and water on the one hand into gum or vegetable jelly, 

 and of carbonic acid and ammonia on the other into proto- 

 plasm or albumen ; that cells increase and multiply by divi- 

 sion and then become changed, for they extend in dimensions, 

 acquire deposit here, undergo resorption there, until all the 

 different tissues are formed ; yet, just as in the animal 

 kingdom, not one of these conditions is met with — transient, 

 it may be, in the object before us — but is the permanent 

 state in the life of some other organism ; and on this rests 

 the foundation of the grand theory of evolution. To no 

 subject could your microscopes be turned with greater profit, 



