582 MEDICAL BOTANY. 



in some degree in bitterness, they may all be considered as medicinal. The 

 British Colleges recognise as officinal, S. fragilis, S. alba, and S. caprcea, 

 but other European species are fully as efficient, as jS. helix, S. russelliana, 

 S. pentandra, and S. purpurea. The United States Pharmacopoeia, there- 

 fore, only recognises the genus without designating the particular species. 

 Among our native Willows, S. nigra, S. eriocephala, and S. conifera, are, 

 perhaps, the most efficient. Michaux speaks of the first of these as affording 

 a powerful bitter root employed as a preventive and cure in intermittents. 



Willow bark varies in appearance and qualities, according to the species 

 from which it is obtained, and the age of the plant. When dried, it is usu- 

 ally in rolled pieces, is fibrous, somewhat flexible, and difficult to pulverize. 

 It has a slight aromatic odour, and a bitter, astringent, but peculiar taste. 

 It has been often analyzed, and the honour of having discovered its active 

 principle is claimed by several chemists, as Buchner in Germany, Fontana 

 and Rigatelli in Italy, &c. Salicin is obtained by several processes, one of 

 which, proposed by Messrs. Tyson and Fisher [Jour. Phil. ColL Pharm. iii. 

 214), is simple, and gives good results. 



Salicin is in silky or scaly crystals, of a white colour, is soluble in water 

 and alcohol, but not in ether. These solutions are neutral, but exceedingly 

 bitter. If sulphuric acid be added to it, a blood-red colour is produced. It 

 possesses tonic properties analogous to the sulphate of quinia, and is said to 

 be less liable to offend the stomach, and affect the nervous system. Notwith- 

 standing the praises bestowed on it by some writers for its febrifuge powers, 

 it is far inferior in this respect to quinia ; and the opinion of it expressed by 

 Ballard and Garrod (Mat. Med. 399) I agree in fully, namely, that it is ineffi- 

 cient as a tonic, when compared to the Cinchona alkaloids ; as a simple bit- 

 ter, however, it appears to rank with Gentian, Calumba, &c, its principal good 

 effect being seen in the improved appetite which sometimes follows its use. It 

 may be mentioned that Quinia is often adulterated with this substance, and 

 that it has been imported for this purpose ; but the fraud may always be de- 

 tected by testing with sulphuric acid. The dose is from ten to thirty grains. 



Populus. — Linn. 



Male : ament cylindrical, loosely imbricated. Bract single-flowered, cuneate, lacerated* 

 Calyx turbinate, oblique, entire. Stamens eight or more, very short, capillary. Anthers 

 drooping, large, quadrangular. Female : flower as in male. Ovary ovate, pointed. Style 

 none. Stigmas four or eight, subulate. Capsule 1-celled, with two concave valves. Seeds 

 numerous, small, ovate, beset with long wool. 



These are trees, with roundish, often cordate leaves ; the petiole often bi- 

 glandular; the buds sometimes balsamiferous, the floral ones appearing earlier 

 than the leaves. The species are most numerous in North America. The 

 bark resembles that of the Willows, and has the same properties ; that of P. 

 tremuloides has been employed in domestic practice with some success as a 

 febrifuge and tonic. In P. balsamifera, it is said to be cathartic, and to be 

 useful in rheumatism and gout. The buds of most of the species are aromatic and 

 abound in a balsamic juice, especially in P. balsamifera; this is collected, and 

 has received the name of Tacamahaca, from its resemblance to the resinous 

 product of the Fagara octandra, which bears that appellation. This balsam 

 is said to be diuretic and antiscorbutic. The buds of the European species 

 are used in the preparation of an ointment in France, &c, which has much 

 reputation in the treatment of wounds, bruises, and tumours. 



