6 STEUCTUEE SIMULATING FEUCTIFICATION. 



ment, when what we may call the ovule, or germ of the 

 future seed, begins to swell. But nothing whatever has 

 been ascertained that throws the smallest light on the 

 process of fecundation. 



Many Algae, perhaps all the red series, are furnished 

 with a double system of fructification, called primary 

 and secondary fruit, — terms which are given for conve- 

 nient 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. 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 son, or in distinct por- 

 tions of the frond. But in many genera, as in Odon- 

 thalia, Dasya, Griffithsia, &c, proper receptacles, of 

 various shapes, are formed for their reception. 



There is, besides, a really anomalous structure, con- 

 nected with an imperfect attempt at fructification, not 

 uncommonly found on several Floridiae. This, to which 

 Agardh gives the name of nemathecium, is a wart-like 

 protuberance, of a very irregular figure, and generally 

 large size, consisting entirely of concentric filaments, 



