^0 INTHODUCTION. 



some of those that appear early in spring, have answered 

 the purposes for which they were created, and have passed 

 away before summer is far advanced. Others, tliough of a 

 dehcate fabric, are more enduring. They outlive the 

 summer, and though they die partly down on the approach 

 of winter, they send out, when spring returns, fresh fronds 

 from the old stumps; the old and the new, though con- 

 joined, retaining a marked difference of appearance during 

 the early part of the' season. Tliose of a woody fabric, like 

 the Great Tanccle, often bear considerable evidence of havintj 

 weathered several winters. The mode of groAvth in La?m- 

 naria saccharina, the Sweet Tangle, and in L, dif/itata 

 is very remarkable. The new growth begins at the base, 

 and pushes the old portion before it. This strikes us as 

 curious, and yet it should be familiar to us, for it is the way 

 in which the nails of our fins^ers and toes are renewed. 



A^ery interesting information respecting the rapidity of 

 the growth of some of the large sea-weeds is recorded in 

 ])r. P. XeilFs article on Fnci, from which, like my prede- 

 cessor, I am glad to borrow the facts observed in tlie course 

 of the arduous undertaking of erecting a beacon on the 

 Carr Kock in the Frith of Forth. The observer was that 

 highly respectable civil-engineer, Mr. Stephenson, and the 



