124 ALGALS. [BOOK i. 



instances it is true, as for example, in Zygnema, the seed is 

 formed from the union of the matter in one filament to that 

 in another, and it has been observed, that the joints of one 

 filament uniformly give out, and that those of another uni- 

 formly receive ; but before conjugation no difference whatever 

 can be perceived between the two filaments. This, which 

 occurs in a tribe of very low organisation, affords the nearest 

 analogy that has yet been noticed with what takes place in 

 higher plants. If it have any real affinity with that process, 

 we may fairly expect the discovery of sexes in the more per- 

 fect tribes; but nothing at all resembling male flowers has 

 been noticed in these. Some old authors certainly invested 

 the air-vessels of Fucus, and others the tufts of hairs that 

 clothe the surface of some species, with this character, but 

 both opinions have been long since given up as untenable. 

 That a transmission of the endochrome from one cellule to 

 another, prior to the formation of seed, occurs in all Algse, 

 seems probable from the fact, that the cellules immediately 

 surrounding the seeds are always colourless and empty, but 

 there is nothing as yet known to prove that one cellule is less 

 adapted than another to receive the endochrome, and form 

 the future embryo, nothing to show that there is any 

 distinction into male and female. 



Many Algse, perhaps all of the red series (Rhodospermese) 

 are furnished with a double system of fructification, called 

 primary and secondary fruit ; terms which are given for con- 

 venient distinction, without intending them to mean that one 

 is of more or less importance than the other, for the seed 

 formed in each is equally capable of producing a new plant, 

 as Mr. J. G. Agardh has clearly shown. "What is called 

 primary is generally placed in capsules, which are either 

 globose or pitcher-shaped, or at least a large number of seeds 

 are collected into compact, sphserical clusters, and immersed 

 in the frond ; in the secondary, on the contrary, the seeds, 

 which are commonly called granules, are usually placed in 

 cloud-like or defined patches called sori, or in distorted por- 

 tions of the frond; but in many genera, as in Odonthalia, 

 Dasya, Griffithsia, &c., proper receptacles of various shapes 

 are formed for their reception. The production of granules 



