SCIENTIFIC NEWS. 309 



Late with, them till they arrive at places suitable for their 

 developement. He compares them in this respect to intes- 

 tinal worms, which can subsist only within the bodies of 

 other animals, From this theory, and the observation, that 

 each parasitic fungus is capable of being propagated only 

 in plants of the same family, he deduces rules of which the 

 farmer may avail himself to avoid the contagion. Eighty- ^ ear 20 ° s I ,e * 

 four species of these fungi were already known, and Mr. 

 Candolle has added more than a hundred to the number. 



In a memoir on alga he has shown, that these marine Alga. 

 plants have no true roots ; that there is no trace of vessels 

 in their organization ; that their whole surface absorbs mois- 

 ture; and chat the greener they arc the more oxigen gas is 

 extricated r from them by light He adds, that the little 

 grains, hitherto considered as their seeds, are merely cap- 

 sules, and contain seeds much smaller, enveloped with a 

 viscous matter, which fixes them where they are to grow. 



Another unsuccessful competitor was Mr. clu Petit- Du Pei ' t_ 

 Tho uars, who resided a long time in tke isles of France and 

 Bourbon, and visited Madagascar. He has begun to pub- 

 lish a Flora of these places, rich in singular plants. His The sago tree 

 observations on the germination of the cgcas.. or sago tree, f^^he palms 

 which some have considered as a palm, others as a fern, and the ferns. 

 have convinced him, that it ought to constitute a separate 

 family, equally distinct from both. 



Mr. Ventenat has published the 20th number of his Gar- 

 den of Malmaison, but ill health has obliged him to take 

 some respite from his labours. 



In Mr. de la Billardiere's 23d number of his Flora of Afruitresem- 



New Holland, he describes a tree by the name atherosperma, ang ?, ut 2« 



r ' meg capable of 



which he considers as belonging to the family of ranunculi, growing in 

 that may probably become useful in France. Its nuts have rance - 

 the taste and smell of nutmegs, and it appears capable of 

 enduring the climate very well. 



Mr. von Humboldt, and his fellow traveller, Mr. Bon- Von Humboldt 

 pland, continue the publication of the plants they observed 

 in South America. The genus meiastoma alone furnished 

 them with so many new species, that they might have filled 

 a. separate work with them. 



They 



