PLANT PHYSIOLOGY. 41 



time and labour to produce; even keeping it up-to-date must 

 be no light task; and possibly if the traveller — being not very 

 far-seeing — looked in at the office and saw many clerks engaged 

 in sorting all sorts of time-tables and confirming multitudinous 

 details relating to small out-of-the-way places, he might wonder 

 whether all that array of facts and figures was really going to 

 help him, and whether the clerks might not have been better 

 employed in some other way But now he has the Guide he 

 can see its value ; in fact he could not do without it, for travelling 

 under any other conditions would mean so much waste of time 

 that his firm could not hope to compete with others who were 

 more adv-anced in their methods. 



This illustrates, in a rather imperfect way, the case for 

 fundamental research into plant physiology; that is, into the 

 internal workings of plants, by which they take up gases from 

 the air, absorb water and salts from the soil, build up new 

 material, grow, and produce flowers and fruit. The illustration 

 may be amplified by a reference to certain problems in agriculture 

 and horticulture which baffle us because we know so little of 

 these matters. What constitutes the difference between a 

 "heavy cropping" and a "light cropping" wheat? Is it a 

 difference in the absorbing capacity of the root, or of the stem 

 or the leaf, or is it a difference in the capacity of the plant to 

 carry the food material in the straw to the ripening grain ? If 

 this knowledge were available, it would open up a new field for 

 the plant breeder; he could aim direct at the differences that 

 matter, and his labours would be shortened and more effective. 

 Again, what makes a plant resistant to a disease ? We know 

 that a disease organism may attack one plant and not another, 

 but we do not know why, or rather our knowledge in the matter 

 is very limited. If we knew more, the problem of disease control, 

 and breeding for immunity, would be robbed of much of its 

 difficulty. Further, we know practically nothing of what it is 

 that influences the formation of flower buds on fruit trees, and 

 yet the success of the crop depends in the long run on this factor. 

 At present we attempt to control the fate of buds by pruning, 

 but our methods of pruning are " rule of thumb " methods, 

 and must continue to be so until we know more of what is going 

 on within the plant, which normally decides how a bud will 

 develop. One more illustration may be given, A fruit-grower 

 purchases a root-stock on which he will graft a scion, and if 

 the root -stock has been properly described it will produce the 

 kind of tree which the grower needs — a tall tree, or a dwarf, 

 or one of medium size. But the only method by which root- 

 stocks can be selected at present is by the long and tedious 



