340 THE YOUNG 



satisfactory, and which will not crack the 

 bottle. The ingredients and " modus 

 operandi " are as follows : — 



ioz. Cyanide Potassium. 



20Z. Plaster of Paris (Powder). 



ijoz. Water (or Sufficiency). 

 Reduce the Cyanide to powder in a mortar 

 then mix with it the Plaster of Paris 

 (Powder), and rub together with sufficient 

 water to form a thick paste, sufficiently liquid 

 to pour out into the (wide-mouthed) bottle. 

 It will set firm in a few minutes, and if any 

 excess of water has been used it will float on 

 the surface and must be poured off. When 

 exhausted it may be renewed simply by 

 adding a few drops of Prussic Acid (strongest) 

 which may be procured by complying with 

 the Pharmacy Act, 1868, regulating the sale 

 of poisons. — H. Andrews, ig, The Terrace, 

 Camberwell. 



BRITISH FERNS. 



By H. Andrews, Camberwell. 



Ferns are flowerless plants ( Cryptogamia ), 

 having fibrous roots, erect or creeping stems, 

 fronds, or leaf-like branches, generally bear- 

 ing sori (seeds). The root is entirely fibrous, 

 and proceeds from the under side of those 

 stems which assume the prostrate or creeping 

 mode of growth ; but when the stem grows 

 erect they are produced towards its lower 

 surface indifferently. The stem forms either 

 an erect stock (candex) by an accumulation of 

 the woody-bases of the fronds, or extends 

 horizontally on or beneath the surface of the 

 soil, and forms what is called a rhizome. 

 The fronds are leaf-like branches, dis- 

 tinguished from "true leaves" by their 

 peculiar development which grows at the 

 apex, while in ordinary leaves the apex is 

 formed first ; they are furnished sparingly 

 with small breathing pores, called stomata, 

 by which they inhale carbonic acid gas (given 

 off by animals), and, being decomposed, the 

 carbon is retained by the plant, while the 

 oxygen is given off (and is absorbed by 



NATUEALIST. 



animals). The fronds of ferns consist of the 

 leafy portion, and the stalk (stipes), the con- 

 tinuation of the stalk through the leafy por- 

 tion is called the rachis, and is generally 

 covered with membranous scales. The fronds 

 are sometimes divided down to the rachis ; it 

 is then called pinnate each of the leaf-like 

 divisions being called a (pinna ), and when 

 this is again divided it is bipinnate. The 

 manner in which the substance of the fronds 

 is traversed is called the venation ; sometimes 

 it is parallel, sometimes forked, and some- 

 times netted. 



Ferns are propagated by spores (sori), and 

 by the development of young plants at the 

 nodes on the upper or outer surface of the 

 frond or rhizome. Spores are minute seed- 

 like bodies, enclosed in small sacs or bags, 

 and attached along the sides or at the ends of 

 the veins of the under surface of the frond, 

 the portion to which they are attached being 

 called the receptacle, and having considerable 

 importance in distinguishing species. When 

 the sori occupy the under surface of the 

 frond they are termed dorsal, and when they 

 project beyond the margin they are called 

 marginal. The spore-cases, or sporangia, are 

 minute roundish-oval bodies, nearly sur- 

 rounded by a vertical band, called a ring, 

 which (when the spores have reached 

 maturity) burst and disperse the fine dust-like 

 spores to germinate. The sori are covered 

 by a thin membranous scale, called an 

 indusium. The sori of some species, however, 

 are naked, and never bear any indusium 

 (ex poly podium vulgaris ). Germination is the 

 development of the sori, under fitting con- 

 ditions, into young plants. Spores differ 

 from "true seeds" in having no embryo pro- 

 vided with special organs, no plumule, or 

 germ of the ascending axis (the origin of the 

 stem), and no radicle, or germ of descending 

 axis (the origin of the root). The spore in 

 whatever position it may happeu to be placed, 

 will throw down its radicle from that part 

 which is bottom-most, and its plumule from 

 that part which is uppermost. A. sori is 



