ANNIVERSAPvY ADDRESS OP THE PRESIDENT. 59 



" Life ! " " Vitality ! " These terms are but convenient cloaks of 

 our ignorance of the somewhat complicated series of purely physical 

 processes going on within plants and animals. "Organization!" 

 Why should the term be applied to the molecular structure of an 

 Amoeba or a yeast-cell, and refused to that of a crystal? And 

 even if we choose to maintain such distinctions as these, must we 

 also insist that they constitute a basis sufficiently broad upon which 

 to establish our classification of the sciences ? 



Unquestionably there are differences between the changes which 

 take place in these wonderful cycles in animals, plants, and minerals 

 respectively. As animals differ from plants in not being able to 

 build up their tissues from the simple compounds of the mineral 

 kingdom, so animals and plants alike differ from minerals in their 

 power of growth by intussusception. 



But perhaps the most striking difference of all between the 

 "vital" processes in animals, plants, and minerals is found in the 

 rate at which they take place. Animals, in consequence of the in- 

 stability of their chemical constitution, are distinguished by an 

 almost ceaseless activity and a consequent brevity of existence. 

 Plants, in the slower rate at which their vital processes take place, 

 bridge over to some extent the tremendous gap between animals 

 and minerals. In these last the vital processes are so prolonged 

 in their manifestations, owing to the stability of their chemical com- 

 position, and they are not unfrequently interrupted by such enormous 

 intervals of time, that they can only be recognized by the geologist. 



The changes which take place in an ephemera are rapid indeed 

 as compared with those going on in the oak-tree among the branches 

 of which it may spend its brief existence ; but in the rocks among 

 which the oak thrusts its rootlets, other processes are going on com- 

 pared with which the life of the oak-tree is as " fast " as that of 

 the ephemera compared with its own. 



Nevertheless the three forms of " life " seem to start pretty much 

 on a level. A solution of nitre in which crystallites are uniting, in 

 obedience to the laws of " polarity," to build up crystals with their 

 regular forms, their molecular structure, and their powers of further 

 development ; a solution of sugar in which the cell of a yeast-plant 

 is living and growing ; and a third liquid with suspended vegetable 

 particles in which an Amoeba is increasing and multiplying, — these 

 three may surely be compared with one another, however unlike 

 may appear to be the higher developments in the three kingdoms 

 to which they respectively belong. 



