1269 



XYLOTOMA. 



YELLOWHAMMER. 



12TO 



stamens inserted Into a globose receptacle; from 2 to 15 carpela on 

 short stipes, flattened, 1-celled, 1-2-seeded, sometimes dehiscent, some- 

 times baccate; the seeds obovate, shining, furnished with an aril. 

 About twelve species of this genus have been described, all of them 

 natives of South America. They are trees or shrubs, with oblong or 

 lanceolate leaves, and axillary, bracteate, 1- or many-flowered peduncles. 

 The wood of all is bitter, hence they are called Bitter- Woods. 



X. fruteacem, Shrubby Bitter- Wood, is a native of Brazil and Quyana. 

 The leaves and wood are aromatic. The seeds also contain an acid 

 aromatic oil, and are used in Guyana by the negroes as a substitute for 

 pepper. 



X. glabra is a native of the islands of Barbadoes and Jamaica. The 

 wood, bark, and berries have an aromatic bitter taste resembling that 

 of the orange seed. Pigeons feed on the berries, and the flesh of these 

 birds is improved in flavour during the season they eat this fruit. 

 When fresh gathered from the tree the berries have an agreeable 

 flavour, and may be eaten with impunity. The wood readily com- 

 municates its bitter flavour. Sugar sent to this country in hogsheads 

 made of it could not be sold on account of the bitter flavour it had 

 acquired. Articles of furniture made of it are proof against the 

 attack' of insects. Persons who work the wood complain of the 

 bitter taste which it produces in their mouths from the dust. 



X. taricea is a native of Brazil. It is called in Brazil Pao d. 

 Embeira and Pindaiba. The bark is fibrous and tough, and is used 

 for making cordage and cables. The fruit is highly aromatic, with the 

 flavour of pepper, for which it might be advantageously substituted. 

 Most of the other species possess the toughness of the bark and the 

 aromatic properties of the fruit. 



XYLOTOMA. [LEI-TIDES.] 



XYPHOSOMA. [BoiD,E.] 



XYRICHTHYS, a genus of Fishes allied to the Labrus, or Wrasse, 

 which the species resemble in general form, but are much compressed 

 and have the head suddenly truncate in front. Their bodies are covered 

 by large scales, but their hands are usually naked. A species which is 

 esteemed as an article of food inhabits the Mediterranean. 



XYRIDA'CEJS, Xyridt, a natural order of Endogenous Plants. 

 The species are herbaceous plants with [fibrous roots. The leaves are 

 radical, sword-shaped, scarious, dilated and equitant at the base. The 

 flowers are arranged in terminal naked imbricated heads ; the calyx 

 is glumaceous, 3-leaved; the corolla petaloid, coloured, with 3 petals; 

 the stamens 6 ; 3 fertile, inserted upon the claws of the petals ; 

 3 sterile, alternate with the petals ; the anthers 2-celled, and turned 

 outwards ; the ovary single, the style bind ; the stigmas multifid or 

 undivided ; the capsule 1-celled, 3-valved, many-seeded, with parietal 

 placentae ; the seed with the embryo on the outside of the albumen, 

 and at the end most remote from tbe hilum. 



As at present constituted this order comprises only the genera Xyris 

 and Abolkoda, The species of these genera are found generally in the 

 hotter parts of the world, chiefly in the tropics of America, Asia, and 

 Africa, Some of the species of Xyrit are found in the southern states 



of North America, X. Jndica is said by Agardh to be used as a remedy 

 in itch and leprosy. 



a e d o 



Xyrii operculata. 



a, an entire plant ; 6, heads of flowers j c, flower separated ; a, fruit ; f, (be 

 lower part of the pericarp. 



XYRIDALES. [ENDOGENS.] 



YAK. [B 

 YAM. [DlOSCOREA.] 



YAPOCK. [MARSUPIATA.] 



YARR. [SPEROULA.] 



YARROW. [ACHILLEA.] 



YEAST, a substance found on the surface of fermenting liquids, 

 and when removed capable of producing fermentation in other liquids 

 susceptible of this action. On placing Yeast under the microscope 

 it presents a number of cells immersed in a mass of amorphous matter. 

 The cells are sometimes single, and at other times several are united 

 together in a kind of chain. These cells are supposed to partake of 

 a fungoid character, and they have been called the Yeast-Fungus, or 

 Ferment-Cells. A genus and species have been constituted for the 

 reception of thia organism, under the name of Saccharomyces 

 Cernince. 



ThU plant has been supposed to be the active cause of fermenta- 

 tion, and the carbonic acid given off during that process has 

 been regarded as the result of the growth of the plant. This 

 teems to be a misinterpretation of the phenomena, as the plant is 

 probably the result of the carbonic acid given off during the process 

 of fermentation rather than its cause. Schleiden supposes that these 

 ferment-cells originate in liquids, independently of other cells, and are 

 truly instances of the formation of cells in a free fluid. He observes 

 however that they have no power of reproducing other cells. The 

 whole subject of the nature of these cells, their mode of production, 

 and tbe history of their development, as well as the phenomena of 

 fermentation in general, require further elucidation. 



(Schleiden, Principle* of Scientific Butany ; Micrographic Dictionary, 

 article* 'Fermentation,' 'Torula,' 'Yeast') 



YELLOWHAMMER, the common name for the Smbertza citri- 

 neUa, Linn. 



Pennant quotes the Bruant ' of Belon (' L'Histoire de la Nature 



des Oyseaux,' p. 366) as this species, and the description seems to 

 warrant the quotation. Belon considers the bird to be the "Mas of 



Tellowhammcr (Emberiza citrinellal. 



