THE LOCALISATION OF ENZYMES IN PLANTS, 

 WITH SOME CONSIDERATIONS AS TO 

 THE DIFFERENTIATION OF GLANDULAR 

 STRUCTURES. 



IN the processes of nutrition which are observable in the 

 vegetable organism, two essentially different modes of 

 procedure have made themselves prominent. In the great 

 majority of plants we find constructive methods most easily 

 visible. The green plant, taking in extremely simple sub- 

 stances by its leaves and its roots, builds them up into more 

 complex ones, till such substances are prepared as are 

 suitable to nourish the living protoplasm. These processes, 

 which we may speak of as constructive, are, however, inter- 

 mittent. The decomposition of C0 2 , and the subsequent 

 elaboration of food material, takes place under the com- 

 bined influences of chlorophyll and sunlight. As soon, 

 therefore, as these cease to co-operate, the processes of con- 

 struction cease. We have such intermittence caused by the 

 alternation of day and night, and by the changes due to the 

 sequence of the seasons. As, however, life continues in the 

 organism, in spite of this intermittence, and as the vital pro- 

 cesses necessitate the continuous nutrition of the living sub- 

 stance, it is evident that there must be a further accessory 

 series of operations to supply the necessary pabulum when 

 construction is in abeyance. While it is active, much more 

 elaborated material is prepared than is needed for the time 

 being, and the surplus is deposited in the tissues temporarily, 

 forming a fund on which the organism may draw in the inter- 

 vals of such construction. We find, consequently, in plants.re- 

 servoirs of nutritive material of various kinds, placed in many 

 different regions ; some, in small amount, intended to carry 

 on nutrition during small periods of time ; others, containing 

 large quantities, destined to serve the plant during longer 

 intervals. The utilisation of these materials, wherever stored, 

 and for whatever period, is a different process from the first 

 one, involving, instead of constructive processes, those of 



