Keegan : The Chemistry of some Common Plants. 169 



of dried specimens gathered in September on rather dry gravelly 

 moorland shows that they yield 2-2 to 2*6 per cent, crude ash 

 which contains 13*9 per cent, potass and soda, 17 silica, 19*2 

 lime, about 6 oxides of iron and manganese, and 2*9 phosphorus 

 ( = 6*6 P 2 0 5 ). The leaves are of a decidedly xerophilous struc- 

 ture and last two or three years ; they are rich in tannin, but 

 devoid of starch and oil in winter. The flowers are of a brilliant 

 purple or bright rose colour in northern latitudes, and yet, 

 notwithstanding the powerful chromogens which minister to 

 their embellishment, can never become blue. Altogether the 

 chemical constituents of the Heather are extremely pronounced 

 and powerfully developed — an admirable and most profitable 

 study for the plant analyst. 



Ragwort. Senecio jacobaea. The ' looped and windowed 

 raggedness ' of the foliar appanage of this plant has suggested 

 the popular name. It seems rather a despicable example of 

 a common weed, but nevertheless it is a special favourite of my 

 own. As it rears its stiff and picturesque stem all solitary or in 

 sparse patches from the bosom of a waste and plough-abandoned 

 field just at the debut of autumn it diversifies the near landscape 

 most affecting-ly and lends an unspeakable piquancy to the 

 solemn scene. The starch of the leaves is not very durable and 

 their carbohydrates are not specially convertible to acids : they 

 contain about 2*5 per cent, carotin, wax, and fat, 10 tannin, and 

 5 resin and bitter principle ; the aqueous extract amounts to 

 25 per cent, and is mostly of mucilage, with some glucose and 

 inosite ; oxalate of calcium is scanty, and there is 13*4 per cent, 

 of ash very rich in potass. There is very little inulin in the 

 plant. The tannin is identical with that universally present in 

 the order Compositse and seems to^be a quinol derivative. The 

 flowers are tinted by carotin enclosed in homogeneous chromo- 

 plastids derived from chloroplastids. 



Enchanters' Nightshade. Circsea lutetiana. This is a 

 sort of hide-away organism lurking in the shade of taller shrubs 

 and hedge-rows, but it is of the most eminent interest to the plant 

 chemist, inasmuch as it is one of our few native herbs that 

 contain that perhaps not very good type of the general characters 

 of tannins, but nevertheless a very distinctive and beautiful one 

 in its reactions, viz., gallotannin. The root contains most, and 

 is also fully charged with starch. There is considerable carotin 

 and resin in the plant, and the dried leaves yield 1 1 -q per cent, 

 of ash, only moderately rich in potass and lime, as behoves its 

 retired habits. 



1902 May 1. 



