32 IXTllODUCTION. 



with great diligence^ have, both by accurate descriptions 

 and by magnificent figui'es_, given us much more accurate 

 ideas respecting the different kinds of fructification. Many 

 Sea-weeds are furnished with a double system of fructifica- 

 tion, called for convenience primari/ and secondary ^ though 

 it is acknowledged that the latter is as capable of producing 

 a new plant as the former. The greater part, if not all, of 

 the red series is furnished with this double fructification, 

 the primarj^j or capsular, on one plant, and the secondary, 

 or granular, on another ])lant. Though the capsules of 

 two different genera and species bear no resemblance to 

 each other, yet there are many modifications of shape, 

 so that they are at once like and unlike, and to become 

 acquainted with the minor differences requires time and 

 attention. 



That our young frieiuls may at one glance have a view of 

 several of the forms which the fructification of iUga? 

 assumes, we have introduced some figures of them, chiefly 

 taken from the elegant plates in Dr. Ilarvey^s ^ Phycologia 

 Britannica' aiul Dr. Greville^s ^Algte Britannica?,^ as both 

 these gentlemen kindly allow me to avail myself of their 

 works. At letter A, fig. 1, there is a small portion of a 

 branch of Volijsq^lionia iirceolata, with a capsule considerably 



