13 BRITISH SEA-WEEDS. 



ring progression, the narrow end of the corpuscle is 

 always in front; while the cilium rising from the co- 

 loured granule trails behind, like a tail." 



In the Red series {RhodospermecB) spores, tetraspores, 

 and antheridia are present, the two former in all, the latter 

 only in a part of the species. The development of two 

 kinds of fertile fruit on diflFerent individuals of the same 

 species is the chief character of the series, and that it 

 should prove to be exactly coincident in general range 

 with'that of colour which had been previously adopted 

 is a striking proof that both systems of classification 

 are correct. It would appear that each species of this 

 series is composed of two distinct parts, each perfect 

 in itself, and capable of independent reproduction, yet 

 both so evidently identical as to form inseparable parts 

 of the same whole. Spores and tetraspores are not 

 " different phases of the same organ, but are in their 

 origin and development perfectly distinct, and formed 

 with the greatest regularity, following fixed laws," nei- 

 ther are they equivalent to the stamens and pistils of 

 dioecious plants of higher Orders. They may rather be 

 considered, the one a true spore, supposed to be ferti- 

 lized by means of an antheridium ; the other, a mere 

 gemmule, or bud of the simplest possible structure, 

 which is cast off by the parent plant, and carries with 

 it sufficient vitality to become the nucleus of a fresh in- 

 dividual. It is far from certain that this is a true ac- 

 count of the nature of these bodies ; and even if it be, 

 there is the further question to be answered, which is 

 the spore and which the gemmule ? On this latter point 

 there is a wide divergence of opinion, and as the evidence 

 on both sides is pretty evenly balanced, it is not wonder- 

 ful that the deductions from it should vary. 



