20 The Science of Life. 



members of a group of individuals who resemble one 

 another in certain characters. There is no absolute 

 constancy in these specific characters, and one species 

 often melts into another, with which it is connected by 

 intermediate varieties. At the same time, the charac- 

 ters on account of which the naturalist gives a specific 

 name to a group of individuals, should be greater than 

 those which distinguish the members of any one family, 

 should show a relative constancy from generation to 

 generation, and should be associated with reproductive 

 peculiarities which tend to restrict the range of mutual 

 fertility to the members of the proposed species. 



The invaluable order and precision introduced by Ray 

 and Linnaeus involved an exaggeration of the constancy 

 and the discontinuity of species, an exaggeration which 

 evolutionary systematists have been slowly endeavour- 

 ing to correct. 



Chapter IIL 

 Classification of Plants. 



Ancient Classification Mediaval Mysticism The Herbalists Cesal- 

 pino Linnceus Development of the Natural System. 



The history of the successive attempts to classify 

 plants is not readily condensed; it occupies over two 

 hundred pages in Sachs's History of Botany, where no 

 words are wasted. Some condensed summary must, 

 however, be attempted, for it is impossible to appreciate 

 the present position without going back to the Jussieus, 

 and the Jussieus force us back to Linnaeus, and Linnaeus 

 back again to Cesalpino. 



The ancient classifications were childish in outline 



and utilitarian in detail. " Herbs, shrubs, and trees "- 



Ancient these three words for many centuries formed 



ciassifica- the outline of the classification; the details 



referred to the diseases which the plants 



were believed to cure. We need hardly say more in 



