[ 35 ] 



VI. Memoir on the Tinctorial Properties of (he Danai's of 

 Commerson,a Sliruh of the Family of the Rubiacice. Ex- 

 truded from the Flora of Madagascar. By Aueert di; 

 Pktit-Thouars. Read in the French National Institute'^. 



JtSoTANYt} like all the other physical sciences, may be 

 considered under two points of view. In the lirst, we ex- 

 amine in plants those things which are pt;rceptible to the 

 senses; and, by comparing the diiVerenccs observed, deduce 

 the means of distinguishing them with certainty iVoin each 

 other. In the second, we endeavour to discover the 

 qualities by which they may be useful to man : — the one is 

 pure botany, the other is the application of botany. Most 

 people who have devoted themselves exclusively to one 

 branch of knowledge, or who have not had an opportunity 

 of acquiring any, being accustomed to judge superficially, 

 value only the second, and consider the first as ahnost en- 

 tirely useless. It ought, however, to be considered as the 

 .foundation of the second; for as it alone establishes, as we 

 may say, the state of a vegetable, it is by it that we cau 

 be assured what plants are capable of giving us that assist- 

 ance for which we may have occiision. The moment, 

 therefore, that the theoretic botanist seems to attend least to 

 the wants of society, is very often that when he is about 

 to announce an important discovery. Being enabled by an 

 exact synonymy to consult all the books which have been 

 written on the object he exaniines, he takes advantage of 

 the knowledge of all nations and all periods. In the 

 second place, if the vegetable he examines have escaped the 

 researches of his prcdtcessors, observation enables him to 

 find out the purpose for which it may be employed. The 

 Ec.ience which he cultivates afl'ords him still another mean 



* from x\\t Jc-:ifnalde Phiisiqiie. Bruir.rMrf, im 13, 

 f This is tilt third memoir of M, ciu Pciic- 1 houars rend in the In- 

 stitute since ins return. In the first, af;cr a short view of a vovage of 

 ttn years to the isles of France, Bourbon, and Madagrfscnr, entirtly dc- 

 vorcd to the natural sciences, and particularly botany, he gives a britf 

 dcscrijjt^on of the deserts of Tristan d'Acngna, which are little fre- 

 quented by navigators. The second is an essay on germination, and tlie 

 ratural relations of the Cyan. Tliis interesting memoir forms part of a 

 first number, which the author has published, and which is to be fol- 

 Jowtdby twelve more, destined to make kn<.\vn the new, or little Known, 

 genera which he had an opportunity of observiot; ; and which are to lie 

 acconip.inied with dissurtatio: s, in the mannei of the present otie, on in- 

 teresting points of vegetable physiology. This first numofr cont.'ir.s also 

 the description and figures of nine plants, uiiich M. du P(:tik-'i tiouar* 

 coiik^dKit «s fuin;i:ig new genera- 



G 2 of 



