236 



KE PORT ON THE 



longer opportunity for discussion, that Dr. Masters' paper be 

 taken as read. The paper itself is appended : — 



On the Root- Structure and Mode of Growth of Primulace.e 

 in Relation to Cultivation/" 

 By Dr. Maxwell T. Masters, F.R.S. 

 For practical purposes it is very serviceable to consider a living plant in the 

 light of a piece of mechanism, constructed and put together to do certain work 

 as efficiently and as economically as circumstances permit. The comparison 

 may serve our purpose without it being necessary to point out where it fails, 

 and wherein lies the great difference between a living machine begotten of its 

 predecessors, and which had the like structure and endowments with itself, self- 

 sustaining, supplying its own power from sun and air and water, built up and 

 adapted by its own energy, and one constructed by the art of man, dependent 

 on artificial means for its support and its power, and with no innate faculty 

 of self-adjustment to varying circumstances. Availing ourselves, therefore, of 

 the comparison we may proceed to discuss what it is our machine is called on 

 to do, how it is enabled by its conformation to do what is required of it, and, 

 incidentally, how we as cultivators may help or mar its action. The Primulacea3 

 will afford us as good illustrations of these matters as any other family of plants. 

 It is the group which is expressly selected to furnish a text for these remarks, and 

 which, moreover, are, as prescribed, to be limited to a part only of the machine 

 — the root. It is permissible, however, on such an occasion to use the term 

 " root " in the broad sense in which it is usually employed by gardeners, and not 

 in the more accurate and strictly limited sense in which it is made use of by 

 physiologists. 



THE REQUIREMENTS. 



What, then, is our machine — the root — called on to do ? In all cases to lay 

 hold of the soil and secure the plant mechanically. How it does this will be 

 sufficiently though incidentally illustrated later on, and is not a subject on 

 which we as cultivators need linger long. The plants we have now to deal 

 with may be lifted out of the ground by frost, but they are hardly likely to be 

 washed away by floods or uprooted by winds. To pot firmly and press the 

 crown firmly into the soil in transplanting are lessons which common expe- 

 rience teaches, lessons which the conformation of the root, to be presently 

 noted, do but accentuate. 



Another universal duty imposed on the root is to feed the plant. There is 

 soil-food and there is air-food. The leaves, stimulated by light and heat, 

 collect and transform the one ; the roots, influenced by heat, absorb and digest 

 the other. How they do these things is beyond the purpose of this paper to 

 explain, but reference to any modern botanical text-book, and in particular to 

 the truly marvellous revelations contained in the chapters on root movements 

 in Darwin's "The Power of Movement in Plants," will supply the information 

 and affords indication of the processes of absorption, of solution, of fermenta- 



* For the communication of numerous specimens illustrative of these notes I am 

 specially indebted to Mr. Dewar, of the Royal Gardens, Kew ; Mr. Barron, of Chiswick ; 

 Mr. Correvon, of Geneva ; Mr. Douglas, and other friends. For some of the drawings 

 I have to thank Mr. Sandgren, lately of the Royal Gardens, Kew. For observations on 

 the development and conformation of the flower of Primulacca?, tte Masters, in 

 Transactions of the Linncean Society, second ser., vol. I., June 7, 1877, p. 285, tab. 3S — II. 



