YAWS 



1626 



YZQUIERDO'S BACILLUS 



Yaws (yawz). See Frambesia. Y., Ringworm, a 

 variety of yaws in which the nodules form rings around 

 the eyes, nose, mouth, or anus. 



Yeast (yest) [ME., zeest, yeast]. The name applied to 

 any of the various species of fungi of the genus Sac- 

 charomyces. It is best known as a ferment thriving in 

 saccharine solutions, breaking up the sugar molecule 

 into carbon dioxid and alcohol. In domestic economy, 

 it is used in leavening bread, the porosity of the latter 

 being due to the escaping carbon dioxid. It is also 

 the essential principle in alcoholic fermentation. In 

 medicine, it has proved of value as an application to 

 foul ulcers and as an internal remedy in putrid fevers. 

 " Of great theoretical interest are some recent re- 

 searches of Hensen's which open out great possibilities 

 in the future. In these investigations he has found 

 that it is possible to produce artificial varieties of yeast, 

 the acquired properties being transmitted from one 

 generation to another, apparently indefinitely ; it is 

 obvious that we have here the beginning, on a micro- 

 scopic scale, of practices which have long been carried 

 out on the higher plants in floriculture." (Frankland.) 

 Y., Beer, the ferment used in brewing beer. It is a 

 more or less pure culture of the saccharomyces cerevi- 

 sivre. Y., Bottom, yeast found at the bottom of a 

 chilled fermentation. Y. -cakes, cakes made of yeast 

 which has been washed, dried, and pressed. Y., 

 German, a mixture of beer-yeast and dry starch, used 

 for baking purposes. Y. -plant, the saccharomyces. 

 Y. -poultice, a fermenting poultice containing yeast. 

 Y., Top, the yeast found on the surface of fermenting 

 liquids. 



Yelk :(yelk) [a variety of yolk~\. See Yolk. 



Yellow (yel'-o) [ME., yelow, yellow]. A compound 

 color of the spectrum. Y. Atrophy of the Liver, 

 malignant jaundice ; acute yellow atrophy of the liver. 

 See under Icterus. Y. Body, the Corpus luteum, 

 q. v. Y. Carmin. See Pigments, Conspectus of. 

 Y. Cartilage. See Cartilage, Reticular. Y. Cells, 

 peculiar cells in the Actinece, which give the spectrum 

 of Chlorofucin. Cf. Chlorophore, Chloroplast. Y.- 

 crowned, having the top of the head yellow. Y. 

 Disease, hemorrhagic malarial fever. Y. Dock. See 

 Rumex. Y. Fever. See Fever. Y. Jack, a popular 

 name for Yellow Fever, q. v. Y. Jasmine. See Gel- 

 semium. Y.-root. See Xanthorrhiza. Y. -shafted, 

 having the shafts of certain feathers yellow. Y.- 

 shouldered, having the bend of the wing yellow. 

 Y. Spot. See Macula lutea. Y. Spot of Soemmer- 

 ing. See Soemmering. Y. -vented, having the vent- 

 feathers yellow. Y. Wash, a lotion consisting of 

 hydrarg. oxychlorid gr. ij, liquor calcis Jj. 



Yellows (yel'-oz). See jaundice. 



Yerba (yer'-bah) [Sp.]. An herb. Y. buena. See 

 Micromeria. Y. mansa, the root of Amenopsis cali- 

 fornica, stimulant, astringent, and tonic. It is employed 

 in California and Arizona for malarial disorders. Dose 

 of the fid. ext. rtLxv-^j. Unof. Y. reuma, the 

 herb, Frankenia grandifolia, common in California. 

 It is astringent and is recommended in catarrhal affec- 

 tions of the urinary tract. Dose of the fid. ext. 

 mjc-xx. Unof. See Frankenia. Y. sagrada. See 

 Lantana brasiliensis. Y. santa. See Eriodictyon. 



Yerbin (yer'-bin) [Sp. , yerba, herb]. Caffein obtained 

 from Ilex paraguaiensis. 



Yew (?/). See Taxus. 



Ylang-Ylang (e'-lang-e'-lang) [E. Ind.]. A tree of 

 the E. Indian islands, Cananga odorata. Its flowers 

 afford a fragrant oil. 



Yok [Eng. colloq.]. The grease obtained from wool. 



Yoke-bone. The malar bone. 



Yolk [also yelk; AS., geolca, yolk, the yellow part]. 

 Popularly applied to the yellow portion of the hen's 

 egg as distinguished from the white. In biolog 

 term yolk has no exact meaning, being sometimes used 

 to designate the Deutoplasm, q.v., alone, while at 

 times the entire ovum proper is indicated. Sec under 

 Ovum. See also Yelk and Vitellum. Y., Accessory, 

 Food, Nutritive, Subordinate, or Supplemental. 

 See Nutritive Vitellus. Y. -cleavage, segmenl 

 of the vitellus. Y.-duct, the vitelline duct. See 

 under Duct. Y.-food. See Deutoplasm. Cf. ( 

 Y., Formative, the active, living portion of the 

 protoplasm of an ovum, with the nucleus it enc!< 

 a whitish disc situated at the animal pole of an 

 ovum, and which undergoes segmentation ami 

 directly into the formation of the embryo. C£ 

 Germinal Disc, Cicatricula, Discus proligcrus. Also 

 called the Tread, Narbe, Hahnentritt. Y. -grains, 

 granules of nutritive substance (deutoplasm) dii 

 produced by the egg-cell itself. Y.-sac, the larger of 

 the two globes formed by the blastodermic membrane 

 in the early development of the embryo. Y. -seg- 

 mentation. Same as Y. -cleavage. Y.-skin, the 

 vitelline membrane. Y., Yellow, the yellow 

 centrally located. Y., White, the albuminous white 

 of the egg. Y. of Wool. See Suint. 



Young (yung) [ME., yong, young]. Being in tl 

 or early stage of life. Not long born. 



Young's Rule. A rule of dosage. Add 12 to the \ 

 age and divide the result by the age, to get tl 

 denominator of the fraction, the numerator of which 

 is I. 



Young-Helmholtz Theory. See Color-sensation. 



Youngling (yung' -ling) [ME., yonglingY A young 

 person. 



Youpon (yu r -pon). See Yaupon. 



Youth (iiih) [ME., youthe, youth]. The period bet 

 childhood and manhood. 



Ypsiliform (ip - sil' - if - orm) [viptldv, upsilon; ' 

 form]. Shaped like the Greek letter T, upsilon. I lyp- 

 siliform. Y. Figure, a peculiar figure seen in the dt 

 velopment of certain eggs, as that of A scan's : 

 cephala. 



Ytterbium (it-tur'-be-um) [Ytterby, in Sweden]. 

 metal, not yet isolated, having the symbol 

 atomic weight of 173.01. See Elements, Ta 



Yttrium (it'-re-um) [Ytlerby,'m Sweden]. Symbol Y, 

 at. wt. 89. A rare metallic element of the a 

 group See Elements, 'J able of. 



Yucca (yuk'-ah) [A. Ind.]. " A genus of lilia 

 plants. Y. filamentosa, Adam's need! 

 Southern U. S., is diuretic. Its tincture is emp 

 in urethritis. Unof. 



Yupon (yu'-pon). See Yaupon. 



Yzquierdo's Bacillus. See Verruga peruana. 



