▪ I. yolk, yelk, n.1
(jəʊk, jɛlk)
Forms: α. 1 ᵹeolca, ᵹeoloca, ᵹioleca, 3 ȝeolke, 4 yholk(e, 4–5 ȝolke, 5 ȝolk, 7 yeolke, yolke, yowlk, yoalk(e, 8– Sc. yowk, (9 yoke), 7– yolk. β. 4–5 ȝelke, 4–7 yelke, 5 ȝelk, 7 yealk, 6– yelk.
[OE. ᵹeolca, ᵹeoleca, -oca, f. ᵹeolu yellow.
The spelling yelk appears to have ceased to be frequent since the third quarter of the 19th century, but it is found in later scientific and technical works. The pronunciation (jɛlk) survives locally; it is not clear during what period or to what extent it has been current in standard English.]
1. a. The yellow internal part of an egg, surrounded by the ‘white’ or albumen, and serving as nourishment for the young before it is hatched.
| α a 1000 Boeth. Metr. xx. 170 Þæm anlicost þe on æᵹe bið ᵹioleca onmiddan. c 1000 Sax. Leechd. II. 38 Hænne æᵹes ᵹeolocan. c 1000 ælfric Hom. I. 40 Sceawa nu on anum æᵹe, hu þæt hwite ne bið ᵹemenged to ðam ᵹeolcan. c 1290 St. Michael 635 in S. Eng. Leg. 317 Ase þe ȝwyte of þe Eye goth a-boute þe ȝeolke. 1340 Hampole Pr. Consc. 6446 An egge yholke. 1398 Trevisa Barth. De P.R. xii. xix (Bodl. MS.), Þe chiken is ibred of þe white and ynorissched wiþ þ⊇ ȝolke. c 1420 Liber Cocorum (1862) 18 Take ȝolkes of eyren þat harde bene. 1486 Bk. St. Albans b vj b, Tempere it with clere wyne and with the yolke of an egge. 1604 Marston Malcontent ii. iv. D 1 b, Seauen and thirty yowlks of Barbarie hennes eggs. 1605 Timme Quersit. i. xiv. 67 The yeolke of the egge..is the true sulphur. 1666 Third Adv. to Painter 18 An Addle-egg with double Yoalk. a 1756 E. Haywood New Present (1771) 158 Beat up the yolks of three eggs. 1842 Tennyson Audley Court 24 A pasty costly-made, Where quail and pigeon, lark and leveret lay,..with golden yolks Imbedded and injellied. |
| β c 1325 Gloss. W. de Bibbesw. in Wright Voc. 150 Le moiel, a yelke. c 1400 Lanfranc's Cirurg. i. iii. 53 Wiþinne þe wounde leie þe ȝelke of an ey. 1560 Whitehorne Ord. Souldiours (1588) 46 b, Oile of the yelkes of egges. 1600 Surflet Country Farm vii. lxv. 895 Putting thereto the yelkes of two egs and a little saffron. a 1625 Fletcher Wife for Month ii. i, Like to poch'd eggs That had the yelks suckt out. 1650 Sir T. Browne Pseud. Ep. iii. xxviii. (ed. 2) 150 That a Chicken is formed out of the yelk of the egge,..the people still opinion. a 1700 Evelyn Diary 29 Sept. 1645, He abounded in things petrified, wallnuts, eggs in which y⊇ yealk rattl'd. 1756 C. Lucas Ess. Waters I. 73 [These] divided and inviscated by the yelk of an egg become miscible in..water. 1864 Reader 5 Nov. 572/2 The embryos of man [etc.] are nourished..by the mother's blood,..and those of birds by the yelk of the egg. 1884 Health Exhib. Catal. 39 The leather is..soaked in liquor made of the yelks of eggs. |
b. in Biol. extended to the corresponding part in any animal ovum, which serves for the nutrition of the embryo (nutritive yolk or food-yolk), and to the protoplasmic substance from which the embryo is developed (formative yolk or germ-yolk): = vitellus 1.
| 1835–6 [see 5]. 1851 Woodward Mollusca 51 After impregnation, the germinal vesicle, which then subsides into the centre of the yolk, divides spontaneously into two. 1879 Haeckel's Evol. Man I. ii. 28 Cephalopods, the embryo of which has a bag of yelk protruding from the mouth. 1889 Geddes & Thomson Evol. Sex viii. 101 The yolk..is more or less readily distinguished from what is often called the formative protoplasm. c 1909 E. Ray Lankester Science fr. Easy Chair xxii. 209 The ‘yelk’ of the bird's egg..corresponds to the black sphere of the frog's egg—the actual germ. |
† c. Bot. = vitellus 2. Obs. rare.
| 1807 J. E. Smith Phys. Bot. xix. (1814) 222 Vitellus, the Yolk, first named and fully illustrated by Gaertner. |
† 2. fig. Centre; innermost part, ‘core’; also, best part.
| 1387–8 T. Usk Test. Love iii. iv. (Skeat) I. 198 Of loue (quod she) wol I nowe ensample make, sithen I knowe the heed knotte in that yelke. |
| 1614 T. Gentleman England's Way 12 Then being the very heart of Summer, and the very yoalke of all the yeare. 1637 Rutherford Let. to Parishioners 13 July, Christ hath the yolke and heart of my love. 1637 ― Let. to J. Kennedy Lett. (1664) 187 Then Christ would..conquer to himself a lodging in the inmost yolk of our heart. 1695 J. Sage Fund. Charter Presbyt. Pref., Wks. 1844 I. 32 The true yolk of the mystery. c 1730 Ramsay To Duncan Forbes iv, Chance gi'es them of gear the yowk, And better chiels the shell. |
3. (Also y. of egg.) Name for a gastropod mollusc of the genus Nerita, from the appearance of its shell.
| 1796 Nemnich Polygl.-Lex. 945 Yolk nerita, nerita vitellus and albumen. 1815 S. Brookes Introd. Conchol. 157 Yolk of Egg, Nerita Vitellus. |
4. a. A rounded opaque or semi-opaque part occurring in window-glass; also, a pane of rough or thick glass. b. A hard or otherwise differentiated nodule in stone, rock, etc. local.
| 1808 Jamieson s.v., Those round, opaque and radiated crystallizations, which are found in window-glass, in consequence of being too slowly cooled, are generally termed yolks in S[cotland]. 1811 Acc. Game Curling 3 Those whinstone nodules..called yolks, on account of their toughness. 1883 Simmonds Dict. Trade Suppl., Yolk, a local name in the Forest of Dean for masses of rotten stone intervening in the grey stone. 1886 J. Barrowman Sc. Mining Terms 74 Yolk coal, or Yolks, free or soft coal. 1901 W. Laidlaw Poetry & Prose 34 They [sc. windows] were of yolks of darkish green, Sae dim they didna need a screen. |
5. attrib. and Comb. in sense 1 b.
The most important are: yolk-bag, yolk-sac, the sac or vesicle inclosing the yolk, esp. when attached to the umbilicus as an organ of nutrition; it is connected with the intestine of the embryo by the yolk-duct or yolk-stalk; yolk-cleavage, yolk-division, yolk-segmentation, the division of the (formative) yolk as the initial process in the development of the embryo; yolk-membrane, yolk-skin, the delicate membrane surrounding the yolk of some ova; yolk plug, a mass of yolk cells partly filling the blastopore in the development of certain fish, amphibians, and insects. Also yolk-coloured adj.
| 1835–6 Todd's Cycl. Anat. I. 560/2 The point of attachment of the yolk-bag [in the Cephalopod], which is suspended from the head of the embryo. 1849–52 Ibid. IV. 1223/2 The central yolk-mass of the body. 1857 Gosse Omphalos xi. 330 The yelk-globe, fastened by its twisted chalazæ, is suspended in a glairy fluid (albumen). 1859 Todd's Cycl. Anat. V. 46/1 The process of yolk-segmentation. Ibid. 51/2 The ovum of the frog..consists of the yolk-ball,..surrounded by a..layer of..albuminous matter. Ibid. [124/1] The germ-forming and yolk-forming portions. 1861 J. R. Greene Man. Anim. Kingd., Cœlent. 15 Many ova are provided with an outer envelope, known as the yolk-sac or ‘vitelline membrane’. Ibid., After fecundation, the ovum exhibits a series of changes inaugurated by the process of ‘segmentation’ or yolk-division. Ibid. 181 After yolk-cleavage the embryo appears rudely cylindrical in form. 1869 G. M. Hopkins Jrnls. & Papers (1959) 189 The other evening..there was a slash of glowing yolk-coloured sunset. 1878 Bell tr. Gegenbaur's Comp. Anat. 18 Special particles—yolk-granules—may appear in its protoplasm. Ibid. 53 Special glands, Yolk glands, are formed from the ovary. 1879 Haeckel's Evol. Man I. x. 284 Connected with the central portion of the intestinal tube by a thin stalk, the yelk-duct. [1881 F. M. Balfour Treat. Compar. Embryol. II. vii. 102 Shortly after the stage represented in fig. 71 B, the plug of yolk, which fills up the opening of the blastopore, disappears, and the mesenteron communicates freely with the exterior by a small circular blastopore.] 1888 Goode Amer. Fishes 190 The comparatively large yelk-sac. 1889 Rolleston & Jackson Anim. Life Introd. p. xxvii, The Gastrula is derived either by invagination or by differentiation of the yolk-cells. 1892 E. L. Mark tr. O. Hertwig's Text-bk. Embryol. of Man & Mammals vi. 117 The inner lamella [of the Triton embryo]..is connected with the mass of yolk-cells.., which lies like a wall in front of the blastopore and even projects into it as the Rusconian yolk-plug. 1898 P. Manson Trop. Diseases xxxvi. 532 The points to be attended to in the diagnosis of ova are size, shape, colour..the presence or otherwise of yolk spheres. 1900 Q. Jrnl. Microsc. Sci. Feb. 7 The thin..yolk-stalk carrying the vitelline artery. 1928 [see induction 9 b]. 1959 Southwood & Leston Land & Water Bugs 299 Fertile eggs [of the bug Capsus ater] commence to develop at once and the grey band of the yolk plug forms just below the operculum about 2 weeks after laying. 1980 Jrnl. Exper. Zool. CCXIV. 323 YSL [sc. yolk syncytial layer] cytoplasm which reaches the yolk plug during epiboly is not a part of the syncytium when gastrulation begins. |
▪ II. yolk, n.2
(jəʊk)
Also yoak, yoke, yok, yelk.
[OE. *eowoca (whence eowociᵹ yolky a.2), corresp. to Flem. ieke (iecke in Kilian; in comb. ie(c)kwoll yolky wool), whence Sc. eik. The spelling of the Eng. word has been influenced by association with yolk n.1]
The greasy substance secreted by the sebaceous glands in the skin of a sheep, which serves to moisten and soften the wool. Also called suint, wool-oil, and (as a chemical substance) lanolin.
in the yolk: said of wool in its natural state, containing the yolk.
| 1607 Topsell Four-f. Beasts 686 The panch of a sucking pig being taken out and mingled with the yolke which sticketh to the inner parts of the skin. 1798 Young's Ann. Agric. XXX. 73 The wool on the moor [sc. Dartmoor] 5 lb. on an average, in the yoak, that is unwashed. 1805 J. Luccock Nat. Wool 81 The power of producing a copious supply of healthy and nutritious yolk is one of the most important qualities of wool-bearing animals. 1858 Simmonds Dict. Trade, Yolk, Yelk, a natural oily secretion or greasy substance in wool. 1884 Jefferies Red Deer viii. 165 The water is fouled by the grease, called the ‘yok’. 1901 Dundee Adv. 17 May 5 [Wool] in ‘the yoke’..was only fetching about 4½d. a lb. |
| attrib. 1808 Vancouver Agric. Devon 343 Eight pounds of yoak wool to the fleece. |
▪ III. yolk, n.3 local.
Also yoak, yoke.
[f. next.]
Hiccup.
| c 1700 Kennett MS. Lansd. 1033 lf. 481 Yoaks, hiccup. 1825 Jennings Obs. Dial. W. Eng., Yokes. |
▪ IV. yolk, yelk, v. dial.
Also 7 yoke, yeke, 8– yock, yeck, etc.
[app. alteration of yox, yex (q.v.) with subsequent assimilation to bolk, belk to belch. In mod. dials. yolk, yoak, yock are south-western and yeck is Sc.]
intr. To hiccup; also, to utter a short cough, as a sheep. Hence ˈyolking, ˈyelking vbl. n. and ppl. a.
| α 1585 MS. Ashmole 208 lf. 237 b Whose vgly locks and yolkinge voice Did make all men a feard. 1598 Sylvester Du Bartas ii. i. iii. Furies 414 Thirst, Yawning, Yolking, Casting, Shivering, Shaking. c 1700 Kennett MS. Lansd. 1033 (E.D.D.) Applied to the short cough of a sheep, as the sheep yekes or yokes, or has a yeking or yoking. |
| β 1527 Andrew Brunswyke's Distyll. Waters H ij b, The same dronke in the maner aforesayd is good for the yelkyng, named Singultus. c 1532 G. Du Wes Introd. Fr. in Palsgr. 954 To yelke, sangloutir. 1590 P. Barrough Meth. Phisick iii. xi. (1596) 117 The meate being..so corrupted, causeth some to yelke. Ibid., When yelking is caused of fulnesse, vomiting is the best remedie. 1653 R. Sanders Physiogn. 191 A yelking which followeth vomiting. |
▪ V. yolk, yolke
obs. forms of yoke.