GREAT STEPS IN ORGANIC EVOLUTION 873 



Many a plant is a very plastic or modifiable creature; and even 

 such a stable structure as a tree, as notably the Bald Cypress (Taxo- 

 dium), may adapt itself almost out of recognition to unusual 

 conditions of life — moisture, drought, wind. etc. It may be that 

 individually acquired modifications hammered on each successive 

 generation of seaweeds on the rising shore, but never taking heredi- 

 tary grip (for that would be Lamarckism!), served as life-saving 

 screens until germinal variations in the same direction had time to 

 establish themselves as appropriate somatic adaptations. 



The migration theory of the origin of land plants, with which we 

 started, is not an easy theory. Freshwater Algce are rather of the 

 nature of "depauperated relics". "To pass from the sea to fresh 

 water implies starvation and deterioration of the output of repro- 

 ductive cells, and hence failure to compensate the wastage of the 

 race, and extinction." Perhaps this smacks a little of ex parte judg- 

 ment; but there is the further difficulty of thinking of simple 

 migrants from pond and swamp beginning de novo the elaboration 

 of structural equipments which many of the seaweeds had already 

 achieved. In place of this theory Dr. Church offers us "the epic of 

 the stupendous epoch of a world-transmigration". "The cells and 

 somatic organisation of all land plants, as also all their reproductive 

 cycles and mechanism, are but the continuation of the mechanisms 

 evolved in the sea, to suit the conditions of life in the sea, as the 

 best response possible under such conditions; and though the 

 mechanism may be emended, modified, or superseded in innumerable 

 details, the primar}?- plan of the architecture and the entire range 

 of general principles of organisation remain essentiall}/ marine." 



Such a view is in general idea in harmony with what we learn so 

 often in the study of animal evolution, that apparent novelties are 

 only very old structures transformed. New lamps out of old has 

 been one of the great methods of evolution. And as to the maternal 

 sea, its currents are flowing still in the life-streams of her children 

 who have so long ago left her. 



ORIGIN OF SEEDS. — One of the great steps in Organic Evolution 

 was the origin of seeds. We take them now in a very matter-of- 

 fact way, as if there had always been seeds, or as if it was easy to 

 give an account of their emergence. Yet we meet few people who 

 can tell us with any approach to clearness what a seed is, and what 

 its significance in the life of plants. All that they are sure about is 

 that seeds are detached from a parent plant and germinate into 

 seedlings. Some will venture a little farther and say that a seed 

 contains an embryo plant, that it has been sojourning for a time in 

 more or less close union with its parent, and that it is in a strange 

 state of arrested development or latent life, which may last for 

 vears. 



