Cultural First Principles. 



By G, S. BOULGER, F.L.S., F.G.S., late Professor of Natural Historx in the 

 Agricultural College, Cirencester. 



IV. Plant-Cells. 



{Continued from 'page 463.; 



Haying discussed the conditions of climate and soil under which we 

 are to plant, we come to the third and most complex and variable 

 condition of which arboriculture is a function, the nature, life, or 

 physiology of the trees themselves. In laying down first principles 

 it is not my object to discuss the individual appearance or botanical 

 characters which are peculiar to each species of forest tree, but I am 

 about to write of those general laws of structure, nutrition, and re- 

 production which it is necessary for every cultivator to know, and 

 which are true alike of the wheat plant or the oak, of the beech or of 

 grass, of the turnip or of the fir tree. I know no book in which these 

 laws are more simple or more accurately explained than in Professor 

 Johnson's " How Crops Grow," edited j by Professors Church and 

 Dyer, a work unfortunately out of print. 



The two principal functions of every organism are its own nutrition 

 and the reproduction of its species ; but before we can understand 

 these vital processes, which constitute the main physiology of the 

 plant, we must be acquainted with their ultimate or minute anatomy 

 or structure. 



Plants are built up of cells. Some of the lowest plants, such as that 

 blue mould with which we are all familiar, or brewer's yeast, which 

 is a plant growing in alcoholic liquids, may consist of single cells, and 

 in the pulp of an orange, a boiled mealy potato, or a pod of the cotton 

 plant, we may isolate the separate cells of complex structures. We 

 find that the vegetable cell consists essentially of a continuous mem- 

 branous coat, without perforations, which in its young state is entirely 

 filled with a yellowish, mucilaginous, semi-fluid, albuminoid substance 

 known as protoplasm. The membrane, or cell -wall, consists of the 

 carbohydrate cellulose (CgH^gOJ ; the protoplasm is a highly com- 

 plex substance, containing nitrogen in addition to the constituent 

 elements of cellulose, with a small proportion of sulphur, and also, 

 probably invariably, phosphorus. As the cell grows the protoplasm 

 becomes almost entirely thrust on one side by a more transparent and 



