THE SMITHSONIAN INSTITUTION. 87 



LECTUHES 



DELIVERED AT THE SMITHSONIAN INSTITUTION, 



SUBSTANCE OF A COUKSE OF LECTURES ON MARINE 



ALG^ 



»Y WILLIAM HENRY HARVEY, 



■OF THE CNIVERSITir OF DCBLIS. 



jTrofessor Harvey visited this countiy for the purpose of studying the marine Algce or 

 sea-weeds of our coast. Two parts of his work have been printed by the Smithsonian 

 Institution, and a tliird will appear soon after his return from his explorations on the 

 coixsts of the PaciSc ocean.] 



Among tli<3 plants which constitute the ordinary covering of the 

 ground, whether tliat covering be one of forests, peopled by vegetable 

 giants, or of the herbage and small herbaceous plants that clothe the 

 open country, we observe that the greater number — at least of those 

 which ordinarily force themselves on our notice — have certain obvious 

 organs or parts : namely a root by which they are fixed in the ground, 

 and through which they derive their nourishment from the fluids of 

 the soil; a ste^n or axis developed, in ordinary cases, above ground ; 

 leaves which clothe that stem, and in which the crude food absorbed 

 by the roots and transmitted through the stem is exposed to the 

 influence of solar light and of the air ; and, finally, special modi- 

 fications of leaf buds called ^Offers, in which seeds are originated and 

 brought to maturity. These seeds, falling from the parent plant, 

 endowed with an independent life under whose influence they germi- 

 nate, attract food from surrounding mineral matter ; digest it ; organize 

 it, that is, convert it from dead substance into living substance ; form 

 new parts or organs from this prepared matter ; and, finally, grow 

 into vegetables, having parts similar to those of the parent plant, 

 and similarly arranged. 



This is tlie usual course of vegetation : seeds develop roots, stems, 

 and leafy branches ; the latter at maturity bear flowers, producing 

 similar seeds, destined to go through a like course ; and so on, from 

 one vegetable generation to another. But, with a perfect agreement 

 among seed-bearing plants in the end proposed and attained, there is 

 an endless variety of minor modifications through which the end is 

 compassed. All degrees of modification exist between the simplest 

 and most complicated digestive organs ; in some, the root, stem, and 

 leaves are so blended together, that we lose the notion of distinct or- 



