132 



THE MECHANISM OF LIFE 



terminal organs will then grow out from the ends of the 

 stems, which may during their further growth become conical 

 or piriform in shape. 



By superposing layers of liquid of different concentration 

 and decreasing density, one may obtain knots and swellings 

 in the osmotic growths marking the surfaces of separation 

 of the liquid. When a young growth in the vigour of its 

 youth reaches the surface of the water, it spreads out 

 horizontally over the surface of the liquid in thin leaves or 

 foliaceous expansions of different forms. 



Kn 



An osmotic madrepore 



The preponderating influence in morphogenesis is osmotic 

 pressure, the osmotic forms varying with its intensity, dis- 

 tribution, and mode of application. Whatever the chemical 

 composition of the liquid, similar osmotic forces, modified in 

 the same manner, give rise to forms which have a family 

 resemblance. The chemical nature of the liquid, however, is 

 not entirely without influence on the form. 'Thus the presence 

 of a nitrate in the mother liquor tends to produce points or 

 thorns. Ammonium chloride in a potassium ferrocyanide 

 solution produces growths shaped like catkins, and the alkaline 

 chlorides feud to produce vermiform growths. 



