87 



It's great analogy to several sea plants, with adi- 

 antum leaves, especially with the genus caulerpa 

 of Mr. Lamoureux, of which the fucus prolifer of 

 Forskal is one of the numerous species, engaged 

 us to rank it provisionally among the sea-wracks, 

 and give it the name of fucus vitifolius. The 

 bristles which cover this plant are found in se- 

 veral other fuci # . The leaf, examined with a 

 microscope at the instant we drew it up from 

 the water, did not present, it is true, those con- 

 globate glands, or those opake points, which the 

 parts of fructification in the genera of ulva and 

 fucus contain ; but how often do we find sea- 

 wieeds in such a state, that we cannot yet dis- 

 tinguish any trace of seeds in their transparent 

 parenchyma. 



I should not have entered into these details, 

 which belong to descriptive natural history, had 

 not the vine-leaved fucus presented a physiolo- 

 gical phenomenon of the greatest interest. Fixed 

 to apiece of madrepora, this Seaweed Vegetates 

 at the bottom of the ocean, at the depth of 192 

 feet, notwithstanding which, it's leaves \v*ere as 

 green as those of our grasses. According to the 

 experiments of Bouguer light is weakened 



* Fuchs lycopodioides, and f. hirsutus. 



t Traits d'optique, p. 256, 264, 346. The fucus vitifolius, 

 at the depth of 32 fathoms, can have received a light only 203 

 times stronger than that of the moon, and consequently equal 

 to half the light of a candle at a foot's distance. But after 

 my direct experiments, the lepidium sativum scarcely takes 



i 



