Keegan : The Chemistry of Some Com7non Plmits. 275 



product, whereas the lichen-starch of certain algae may be 

 regarded as a degradation product of cellulose. It is not 

 apparently that there is a drain on the fungal element by the 

 alga in respect to proteid matter that occasions these distinctive 

 differences, but rather that the true unassociated fungus 

 absorbing its nitrogen mainly from organised bodies in a state 

 of decomposition this constituent may lend itself readily to that 

 particular form of degradation in the body of the plant which 

 yields alkaloids and other poisonous principles. 



Common Polypody (Polypodium vulgare), — This may be 

 regarded as an evergreen among ferns. Unlike most of its 

 tribe it shuns the steamy warmth and moist sensations of the 

 woodland dell, and breaks out boldly in the open, dry, sunny 

 places however artificial, such as stony unmortared walls, roofs, 

 towers, steeples, or old trees. It nourishes itself independently 

 of any symbiotic fungi (mycorhiza) and hence there is great 

 development of the root system, a copious water-current, a 

 taking up of nitrogen in the form of nitrate, and a free 

 cultivation in soils poor in mineral salts. The rhizome is 

 charged w^ith starch, and certain of its cells contain a finely 

 granular protoplasm and numerous droplets of fat-oil, the 

 brown cells are formed of vasculose and are not lignified ; 

 there is a large quantity of glycyrrhizin (same as in liquorice) 

 which is a nitrogenous glucoside of a sweet taste and 

 yellow colour, and forms a jelly with water, also an iron- 

 greening tannin, and some saponin and resin. The fronds 

 contain about 3 per cent, wax with some fat-oil, but very little 

 carotin or resin, also 4*4 per cent, tannin, free phloroglucin, 

 mucilage, and oxalate of calcium (in the nerves and petiole 

 only), and 4*5 per cent, of ash which in November had 43*5 per 

 cent, soluble salts, 5*9 silica, 177 lime, 6 "8 magnesia, 9 P"^0% 

 and 7'6 chlorine. In the old withered frond of late April the 

 silica rises only to 8*3 per cent., in marked contrast to that of 

 bracken which reaches in October the enormous figure 53. We 

 see, therefore, how sturdily this cold-enduring plant maintains 

 an active vitality all through the winter rigour. 



Yellow Loosestrife (Lysimachia vulgaris). — This gay and 

 steadfast plant affects the water-side ; it springs up year by 

 year with irresistible persistency on certain well-defined spots — 

 the stony marge of lake and beck, and assumes a certain air of 

 brilliant gaiety incident to a rather showy panicle of golden 

 flowers. The root possesses secretion-glands with a red-brown 

 content, its cortex is rich in starch and has abundant tannin. 



1905 September i. 



