INTRODUCTION TO CllYPTOGAMIC BOTANY. 229 



transformed portions of the frond, thicker and more jviicy than 

 the rest, called receptacles. The fruit consists of two kinds of 

 bodies; larger cells filled with endochrome, and smaller (anthe- 

 ridia) containing a number of spermatozoids, furnished with 

 two flagelliform appendages. These sometimes grow together 

 in the same plant, or occur on distinct individuals. The endo- 

 chrome of the larger cells is at first simple, but it subsequently 

 divides* into two, four, or eight distinct spores. It has two 

 distinct coats besides that of the spore cell. The coats are 

 united at the base, and when the spores are ready for disper- 

 sion the inner coat bursts through the apex of the outer, 

 dragging with it a portion of this latter in the form of a little 

 peduncle. The immediate covering of the spores at length 

 bursts, and they are set free. Before the rupture of the sacs, 

 the spermatozoids sometimes swarm on the surface, and in this 

 case derange their perfect evolution. When the spores are free, 

 their surface is equally occupied by the spermatozoids, which 

 by their motion roll them over, so as to appear like zoospores. 

 In this state they are entirely destitute of any envelope, as is 

 the case with the spores of Vaucheria before impregnation. 



217. The real nature of the active granules in Fucus ser- 

 ratus, F. vesiculosus, and F. nodosus, &c,, has been fully 

 proved by M. Thuret. Their spores and antheridia were care- 

 fully collected from plants out of which they had oozed in a 

 moist atmosphere, and then placed in salt water, and either 

 kept apart or purposely mixed. In the former case, after a 

 few days the spermatozoids collected in swanns, retaining 

 their power of locomotion from one to three days, at the end 

 of which they perished, while the spores continued healthy 

 for eight days, and even made an attempt to germinate, with- 

 out, however, any division of the endochrome, and then 

 perished. When, however, the cognate spores and anthe- 

 ridia were placed together, the spermatozoids soon swarmed 

 round the spores, retaining their motion as before, from one 

 to three days, and then gradually losing their activity, while 

 the spores themselves .began to change their appearance ; the 



* lu Uimanthalia, Ilalidri/s, &c., it does not divide at all. 



