601 



EQUISETACE^E. 



EQUISETUM. 



stone in the Sewalik Mountains at the southern foot of the Himalayas, 

 between the Sutlej and the Ganges. Several species have been recorded, 

 but we must not forget the opinion of Cuvier, who thought there 

 were not sufficient data for specific distinctions. He informs us that 

 he had carefully compared the skeletons of many varieties of horses, 

 those of the Mule, the Ass, the Zebra, and the Quagga, and he never 

 could find a character sufficiently fixed to enable him to pronounce on 

 a species from an isolated bone. Size, he remarks, furnishes but 

 incomplete means of distinction : horses and asses vary much in this 

 particular, from their state of domestication ; and he adds, that 

 though he had not yet procured the skeleton of a Dshikketee, he 

 doubted not its resemblance to that of the other species as much as 

 they resembled each other in the same particular. He therefore 

 seems to be borne out in his opinion that comparative anatomy 

 cannot solve the question whether the horse whose remains are found 

 in a fossil state resembled the horses of the present day. The fossil 

 species recorded by authors are Equ.ua fossilis (E. Adamiticus of 

 Schlotheim) ; E. (Caballuf) primigenius ; . (Afulu*) primigeniui ; E. 

 ( A fin IM) primigmiiu. Professor Owen, in his ' British Fossil Mammals ', 

 has described three species of Equidw Eqwu& fossilis, E. plicideng, 

 and Asinus fosttiit. Their remains were all found in the Tertiary 

 Formations of England. He thus concludes his remarks on the 

 Fossil Equidce: 



" In reviewing the general position and distribution of the fossil 

 remains of the genus Equus, we find that this very remarkable and 

 useful form of Pachyderm first made its appearance with the 

 Rhinoceros during the Miocene periods of geology. From the pecu- 

 liar and well marked specific distinction of the primoggnial or 

 slender-legged horses (Hippotherium), which ranged from Central 

 Europe to the than rising chain of the Himalaya Mountains, it is 

 most probable that they would have been as little available for the 

 service of civilised man as is the Zebra or the Wild Ass (Equtu 

 Jlemionut) of the present day ; and we can as little infer the docility 

 of the later or Pliocene species, E. plicidens and E. fostilis, the only 

 ones hitherto detected in Britain, from any characters deducible from 

 their known fossil remains. There are many specimens however that 

 cannot be satisfactorily distinguished from the corresponding parts of 

 the existing species, E. catialliu, which with the Wild Asa may be 

 the sole existing survivors of the numerous representatives of the 

 genus Equus in the Europeo-Asiatic continent during the Pliocene 

 period. The species of Equut which existed during that geological 

 pi-rim I in both North and South America appears to have been blotted 

 out of the Fauna of those continents before the introduction of man. 

 The aborigines whom the Spanish conquistadors found in possession 

 of Peru and Mexico had no tradition or hieroglyphic indicative of 

 such a quadruped ; and the horses that the invaders had imported 

 from Europe were viewed with astonishment and alarm. 



" The researches of Mr. Darwin and Dr. Lund have however indis- 

 putably proved that the genus AVyitiw was represented during the 

 Pliocene period by ft species (E. curviderw) which is shown to be 

 distinct from the European fossils and the existing species. Fossil 

 remains of the Horse have likewise been discovered in North America. 

 The geographical range of the genus Equus at the Pliocene period 

 was thus more extensive than that of the Rhinoceros, of which both 

 the extinct and existing species are confined to the continents of the 

 ( Mil World of geography. The Horse, in its ancient distribution over 

 both hemispheres of the globe, resembles the Mastodon, and appears 

 to have become extinct in North America at the same time with the 

 If. gigantnu, and in South America with the M. Andium and the 

 Megatherium. Well may Mr. Darwin say, ' It is a marvellous event 

 in the history of animals that a native kind should have disappeared, 

 to be succeeded in after ages by the countless herds introduced with 

 the Spanish colonist.' " 



EQUI.SETA'CE/E, Hortctailt, a natural order of imperfectly- 

 formed Plants whose real affinity is uncertain, and the nature of 

 whose parts of fructification is not yet understood. By Linnaeus and 

 almost all botanists they are referred to the Cryptogamic class. With 

 Ferns their relation is not obvious. In the arrangement of their 

 reproductive organs they have a striking resemblance to Xamin, and 

 in their general aspect to Ephedra or Camarina. Dr. Lindley regards 

 them as a high form of the muscal alliance, and places them near to 

 Marchantiacete. Only one genus is known, the stems of a species of 

 which are employed in the shops under the name of Dutch Rushes. 

 They are hollow-stemmed leafless plants, with a cuticle composed of pure 

 srlcx. In lieu of leaves they have toothed sheaths, each of which has as 

 many series of imperfect spiral vessels passing into fistula) of the stem 

 an there are toothings. Their fructification grows in terminal cones, 

 consisting of stalked peltate scales, having on their lower side small 

 canes wherein are lodged minute oval or round green bodies, sur- 

 rounded by four elastic hygrometrical yellowish-gray granulated 

 clavate threads. By all botanists the central green body is admitted 

 to be a seed or spore. The nature of the clavate threads is disputed ; 

 they are usually called Elaters, and are compared to the elastic spiral 

 threads bearing that name in Jungcrmanniofece ; but there is no proof 

 of such being their nature, and there is an opinion that they are 

 ni'limentary stamens. 



These plant* are found in ditches and rivers in most parts of the 

 world, within and without the tropics. None of them are of any 



medical use ; they are said to be slightly astringent and stimulating, 

 but are not now employed. The stems of some of them are used for 

 polishing furniture and household utensils, owing to their siliceous 

 properties. According to the observations of John of Berlin they 

 contain 30 per cent, of siliceous earth. The quantity of silex contained 

 in the cuticle of E. hyemale is so great that Sivright succeeded in 

 removing the vegetable matter and retaining the form. [EQUISETUM.] 



Eiinisctum Jltiiititite. 



1, a sterile branch ; 2, a fertile branch in fructification ; 3, one of the peltate 

 scales ; 4, the game viewed from below ; 5, two of the cases very much magnified ; 

 6, an ovule with the four supposed anthers. 



EQUISE'TUM (from 'equus,' a horse, and 'seta,' a hair or bristle, 

 from the character of the leaves), a genus of Plants, the type and 

 only genus of the order Eqiiisetacece. The species are leafless branched 

 plants, with a striated fistular stem, articulations sheathed at the 

 base ; the sporules are surrounded by elastic clavate filaments, and 

 inclosed in thecoo arising from the peltate scales of terminal cones ; 

 the vernation is straight, and the cuticle abounds in silex. 



E. hyemale, Dutch Rush, has a simple stem, very rough, with from 

 14 to 20 slender furrows : the sheaths close, whitish, but the top and 

 bottom black ; the teeth slender, black, deciduous. This plant is a 

 native of England, Scotland, and Ireland, as well as the continent of 

 Europe. It is almost unknown in the middle and southern English 

 counties, and is only sparingly distributed anywhere. It was recom- 

 mended as a medicine by the ancients, and the earlier herbalists 

 quoted them as authorities for its virtues ; but it is not now used in 

 medicine. It appears however to possess tannin, and to act as an 

 astringent. It is supposed to be injurious to cows, and is said to 

 cause their teeth to drop out, but horses eat it with impunity. This 

 plant more than any other species is used for the purposes of polishing. 

 Lightfoot says that in Northumberlaud the milk-maids scour their 

 pails with it. It is also used for the purposes of polishing wood, 

 bone, ivory, and various metals, particularly brass, and is brought 

 into this country from Holland, where it grows abundantly in large 

 quantities, and is sold in the shops of London under the name of 

 Dutch Rush. Mr. Newman thinks however that the Equisetum 

 brought from Holland is a different species from the British E. hyemale. 

 The stems of this plant contain large quantities of silex, and in the 

 ash left after burning it forms as much as 97 per cent. On subjecting 

 a portion of the cuticle of this species to the analysis of polarised 

 light under a high magnifying power Brewster detected a beautiful 

 arrangement of the siliceous particles, which are distributed in two 

 lines parallel to the axis of the stem, and extending over the whole 

 surface. The greater number of the particles form simple straight 

 lines, but the rest are grouped into oval forms connected together 

 like the jewels of a necklace by a chain of particles, forming a sort of 

 curvilinear quadrangle, these rows of oval combinations being 



