Editing Candling

{{Short description|Method of observing an embryo inside an egg, using a bright light source}}
{{other uses|Candle (disambiguation)}}
{{One source|date=June 2014}}

[[File:CDC microbiologist demonstrating how to candle an embryonated chicken egg.tiff|thumb|Candling an egg]]

'''Candling''' is a method used in [[embryology]] to study the growth and development of an [[embryo]] inside an [[egg (biology)|egg]]. The method uses a bright light source behind the egg to show details through the shell, and is so called because the original sources of light used were [[candle]]s.{{cn|date=May 2014}}

The technique of using light to examine eggs is used in the egg industry to assess the quality of edible eggs.<ref>{{cite web
| url = http://urbanext.illinois.edu/eggs/res26-candling.html | title = Candling eggs | publisher = [[University of Illinois system|University of Illinois Extension]] | quote = Eggs are candled to determine the condition of the air cell, yolk, and white. Candling detects bloody whites, blood spots, or meat spots, and enables observation of germ development. Candling is done in a darkened room with the egg held before a light. The light penetrates the egg and makes it possible to observe the inside of the egg. Incubated eggs are candled to determine whether they are fertile and, if fertile, to check the growth and development of the embryo | date=2019| accessdate = 2012-06-06}}</ref>

<gallery>
File:CDC PHIL 10147 – candling, non-fertile egg.jpg|A non-fertile chicken egg, with only a round yolk sac
File:CDC PHIL 10148 – candling, fertilized egg, non-viable.jpg|A non-viable fertilized chicken egg, with a thin blood ring encircling the yolk
File:CDC PHIL 10149 – fertilized egg, 11 days old.jpg|A fertilized chicken egg, 11 days old, with blood vessels surrounding the yolk
</gallery>

==In plants==

[[File:Pehr_Hilleström-Äggprovet.jpg|thumb|left|Candling an egg using a candle]]

This technique can also be used to assess the quality and development stage of certain translucent plant [[seed|seeds]], especially those of [[Lilium|Lilies]] and their close relatives. Ripe, viable seeds have a visible [[embryo]] within them when viewed in transmitted light, so good seeds can be sorted out from the non-viable seeds and chaff, if desired. Candling is a highly useful method with certain species that [[Lily seed germination types|germinate erratically or very slowly]], as seed germination causes the embryo to enlarge. Candling can thus be used to estimate the optimal time for planting seeds that are being [[Stratification (botany)|stratified]]. Care must be taken during candling, as drying or overheating will kill the developing seeds.<ref>{{cite web
| url = http://www.pacificbulbsociety.org/pbswiki/index.php/LiliumSeeds
| title = Pacific Bulb Society - Lilium seeds
| publisher = Pacific Bulb Society
| access-date = 20 February 2016}}</ref>

==In lutherie==

[[File:Luthier_candling.jpg|thumb|A luthier candling a soundboard to check thickness in the area where the rose will be carved in between adjustments.]]
In [[lutherie]], '''candling''' is sometimes used to check the thickness of the soundboard in various places, especially on lutes and historical guitars. This is especially necessary because these instruments have soundboards which vary in thickness, for instance the area where the [[Rosette (music)|rose]] is carved.<ref>{{Cite web|url=https://www.lutesociety.org/pages/building-lute-original-methods|title = The Lute Society: Building Lute Original Methods}}</ref> It is also used to check for any flaws in the wood, or to check how tight a joint is, for instance on the centre seam of the soundboard.<ref>{{cite web |url=https://www.liutaiomottola.com/construction/Top.htm |url-status=dead |archive-url=https://web.archive.org/web/20101009024335/http://liutaiomottola.com/construction/Top.htm |archive-date=2010-10-09 |title=Building the Top Plate of the Flattop Guitar}}</ref>

Traditionally, a candle would be used, hence the name, but usually nowadays a modern light is used, as this is less of a fire risk.

==References==
{{reflist}}

==External links==
*[http://www.pacificbulbsociety.org/pbswiki/index.php/LiliumSeeds Pacific Bulb Society] – Information about candling lily seeds
*[http://cdm16884.contentdm.oclc.org/cdm/singleitem/collection/p16884coll113/id/174/rec/3 Candling and grading manual for shell eggs] – 1951 publication on egg candling by Kansas State Board of Agriculture

{{Chicken}}

[[Category:Poultry farming]]

{{poultry-stub}}