394 THE WONDER OF LIFE 



his important work on Fluid Crystals in 1904, the conception 

 of crystals has had to be profoundly altered. For he 

 introduced us to what he called the ' new world ' of crystals 

 that are mobile and liquid, yet not separable by any break 

 from those that are rigid and solid. The fundamen- 

 tal character is the power of growing, and Professor 

 Lehmann thinks that this may be, as it were, utilized in the 

 growth of organisms. He figures the beautiful growths 

 of purely inorganic ' siUcate- vegetation '. But what must 

 be definitely borne in mind is that the crystal can only 

 grow larger at the expense of material the same as itself. 



Organic growth is essentially a regulated increase in 

 the amount of hving matter (protoplasm) and intimately 

 associated substances. It is much more than accretion, 

 it is an active process of seM-increase. UrJike a crystal's 

 growth, it comes about at the expense of materials different 

 from the growing substance — often very different, as in 

 the case of plants, which feed on air, water, and salts. 

 Unhke mere expansion, it is regulated in relation to the 

 organism, or organ, or cell that is growing. In all multi- 

 cellular organisms growth is associated with cell-division, 

 for when the individual cell reaches its hmit of growth it 

 divides into two. 



As to the conditions of growth, the first is Nutrition. 

 Living involves continual wear and tear and not less 

 continual recuperation ; growth depends on there being 

 a surplus in the process of self-renewal. In other words, 

 it is a fundamental condition of growth that income 

 should be greater than outlay. Thus the enormous bulk 

 of many plants — ^Hke the Big Trees of California — is in part 

 dependent on the fundamental fact that the income of the 

 plant is always high above its expenditure. Animal giants 



