1884.1 LAWS OF GROWTH. 291 



that other fifty may arrive at maturity and excellence. Seeds arc 

 sown to which she denies the conditions of germination, and fruits 

 are dropped to rot unrelished. Prodigal Nature ! All this waste for a 

 few timber trees ? Yes, partly for that, partly for guidance to all 

 Avho may grow timber trees, and partly that all who look may learn 

 how timber trees are grown. Not in vain does Nature sow thickly, 

 if we learn thereby to plant closely. It is not wrong in her to kill 

 thousands, while we have to learn how and when to remove what .she 

 would kill — to cherish things seemingly worthless till we learn not to 

 despise them. We have no cause to complain of waste that teaches 

 the rudiments of thrift. 



From such a forest we learn that the laws of form are the old laws 

 of equilibrium and motion. The forms themselves are the resultants 

 cf forces whoso magnitude and direction may be computed by means 

 of the well-known parallelogram and polygon of forces. Growth, 

 gravitation, light, shade, cold, concussion, Src, are the forces on 

 whose directions and magnitudes computation is exercised. "What 

 goes by the name of hahit is seen to be not so much a determination 

 of internal laws of growth, as of external conditions. Contiguity 

 is seen to be not merely destructive, but also directive, of sidegrowtb, 

 so that trees grown near to each other are invariably taller than trees 

 of the same species grown in solitude. Light and shade are seen to 

 have meanings that cannot be learned from pictures, and functions 

 that are not confined to artistic contrasts : they are seen to be not 

 accidents for which Nature expresses now gladness and now sorrow, 

 but the ready instruments by which her grandest works are reared, 

 and her most benign products placed at the disposal of men. 



From such a forest we also learn the cultural value of nurses. One 

 knows not whether he is more amused than baffled in trying to evolve 

 from writings on sylviculture the true theory of nurses. 



By some writers we are led to suppose that to shelter other trees 

 from storm is their primary function ; but those who suggest this idea 

 also prescribe for the employment of nurses in the most sheltered 

 positions. Others seem to suggest that to preserve warmth, by 

 excluding cold, is the chief use of nurses ; but as forests of warm 

 climates require the presence of nurses as much as forests of tem- 

 perate climates do, the preservation of heat cannot be the function 

 we are in search of. Besides, a close forest, though warmer in 

 winter, is colder in summer than the open plain or hillside. Trees 

 are equalizers of temperature. Every forest is a kind of climatic 

 equation. Other writers seem to suggest that the principal function 

 of nurses is the choking of rank herbage on the floor of a forest, 

 and the killing of certain branches on the trees intended for timber. 

 We admit the power of nurses to do these things, but cannot accept 



