672 



MEDICAL BOTANY. 



dysentery and other bowel affections. (Flor. Med. Antill. iv. 73.) L. selago 

 is regarded as very active, and some cases of poisoning with it have been 

 recorded ; in small doses it acts as an emeto-cathartic, and in over quantity like 

 the acro-narcotics. A decoction is employed in Sweden to destroy vermin 

 on domestic animals. When mixed with lard it forms an irritating ointment, 

 which has been used as a dressing to foul ulcers, and to keep blisters open. 



L. catharticum of Peru is regarded in that country as a most violent 

 purgative, and is said to have been administered with much suceess in 

 elephantiasis. L. phlegmaria is reputed to be aphrodisiac, and L. hygro- 

 metricum, according to Martius, [Jour. Chim. Med. vi. 213,) is eminently 

 so. This plant is remarkable for its hygrometrical properties, closing its 

 leaves so as to form a ball, when dry, and spreading them out when 

 moistened. 



Class VI. — Thallogens or Thallogenous Plants. 



Flowerless plants, wholly composed of cellular tissue, with no distinction of stem, root 

 or leaves; not growing by buds, nor furnished with reproductive organs analogous to 

 flowers. 



Group LIV. — Algales. 



Order 122.— FUCACE^.— Lindley. 



Fig. 324. 



Fluviatile or maritime plants. Frond monosiphonous, consisting of a single cell, or 



polysiphonous, of several cells, various in 

 form ; barkless or with a bark, jointed or con- 

 tinuous, thread-shaped or of various configu- 

 rations. Mode of growth by a division of 

 the cells ; branching by lateral increase. 

 Mode of increase by spores, contained in 

 superficial cells, which are often vesicular, 

 growing singly out of a thin colouring mat- 

 ter ; and consisting of a single nucleus in- 

 cluded in its proper cellular membrane, (epi- 

 spore), and discharged by the opening of a 

 transparent mother cell (perispore). Vesi- 

 cles scattered through the whole frond, or 

 seated on particular parts, of it, sometimes on 

 a particular receptacle. 



The Fuci or sea-weeds are found in 

 all parts of the world ; some of them ap- 

 pear almost to be cosmopolites; others 

 occur in immense beds floating on the 

 surface of the sea in certain limits, and 

 are often of gigantic size ; thus Scyto- 

 siphon filum, common in the North 

 Sea, is frequently from 30 to 40 feet in 

 length. Bory de St. Vincent states 

 that Lessonia fuscescens is from 25 to 

 30 feet long, with a trunk as thick as a 

 man's thigh. But the giant of the race, 

 and in fact of the vegetable kingdom, is Macrocystis pyrifera. This is said 

 to attain a length of 1500 feet; the leaves are long and narrow, and are 

 furnished with vesicles filled with air by which they float; the stem is slender, 

 not being thicker than the finger. 



Fucus vesiculosus. 



a Upper part of frond, b Section of a receptacle, 

 c Tubercle, d Filaments and. sporangia com- 

 posing the tubercle, e Filaments which issue 

 from pores on the surface of the frond. 



