ADJUSTMENT OF FOECES. 289 



cuttings were quite ready for growth, it told with the utmost 

 possible effect. \ 



What is demanded when cuttings of plants are to be struck, 

 is a due adjustment of heat, light, and moisture. The first 

 stimulates the vital processes, the second causes the formation 

 of matter out of which roots and leaves are to be organized, the 

 third is at once a vehicle for the food required by the cutting, 

 and a part of it. The great difficulty is to know how to adjust 

 these agents. 



If the heat is too high, organs are formed faster than they 

 can be solidified; if too low, decay comes on before the 

 reproductive forces can be put in action. "When light is too 

 powerful, the fluid contents of the cutting are lost faster than 

 they can be supplied ; when too feeble, there is not a sufficiently 

 quick formation of organizable matter to construct the new 

 roots and leaves with. If water is deficient, the cutting is 

 starved ; if over- abundant, it rots. 



It is, then, the adjustment of these forces to the peculiar 

 nature of the cutting to be acted upon that constitutes the art 

 of propagation. It is this which theory cannot supply, but 

 which depends upon skill and experience. If any part of the 

 operations of cultivation can be called empirical, it is this. 

 And yet the operator is not without rules to guide him ia this 

 adjustment ; the misfortune is, that they are too general. The 

 __3o|iei:_A .xuttiag»_jJie_j]Qncker ^mjist^b^ excitement and, 



application of the formative process. The more hard and 

 "woody a cutting, the slowei; wiU be the operation. 



The great enemies of the propagator, says Mr. Neumann, 

 are rotting and drying ; for this reason cuttings are preserved 

 in the midst of a temperature and humidity always equal, the 

 evaporation of the soil is hindered, and the perspiration of the 

 cuttings is prevented. Heat, light, and moisture being the 

 agents to whose assistance we must look for success, and by 

 whose mismanagement the hopes of the gardener are ruined, it 

 is of the first importance to determine how each can be best 

 and most efficiently controlled. And first of heat. 



We know that plants are distributed over all parts of the 

 habitable globe ; that in neighbouring countries the species are 



