256 VEGETABLE ORGANOGRAPHY. 



tubercles are produced at the period of fructification ; 

 these are pierced at their apex by a round pore ; and I 

 have seen in F. Confervoides, in a fresh state, the spo- 

 rangia come out through it in intermittent jets ; these 

 sporangia do not differ from those of F. vesiculosus ; but 

 we find in the tubercle, where they are lodged, nothing 

 like the bristly masses or even the viscid mucus of which 

 I have spoken above, This is my principal objection to 

 the theory of Correa ; and if one wished to admit the 

 existence of a fecundating fluid, it must be said that it 

 is that which is found with the spores in the sporangia; 

 for it is this alone which is observed in all the Thalas- 

 siophytse. F. pinnatifidus only differs from those which 

 I have mentioned in the sporangia being pear-shaped 

 instead of oval. The fructification of Ceramium presents 

 little difference from that of the Fuci with lateral tuber- 

 cles ; but I have not sufficiently studied it to describe it. 

 As for the marine Ulvae, they only appear to differ from 

 the Fuci in their sporangia, which are oval, and perfectly 

 like those of.F. vesiculosus and F. Confervoides, growing 

 in parcels in the tissue of the frond, and, as this is not 

 pierced, they can only come out by the destruction of 

 the tissue ; it is this which causes the regular holes, often 

 found in old species of Ulva. 



It results from these descriptions, that all the Thalas- 

 siophytae have spores contained in a membranous spo- 

 rangium, floating in a viscid fluid which, at maturity, 

 sinks to the bottom of the water, and serves probably to 

 attach them to rocks. At germination, these spores are 

 developed by forming a small cup, more or less regular, 

 which disappears in most, but is met with in Fucus 

 Loreus, for example, at an advanced age. The spor- 

 angia are collected several together, or lodged in the tissue 

 of the leaf, as in Ulva and certain Fuci, or in lateral 

 tubercles, as in the other Fuci and Ceramium ; they come 



