STRUCTURE OF EGGS. Ill 



whites are distinct is from hence manifest, that, the 

 outward bark or shell being taking away, if you 

 pierce both the subjacent membranes, you shall see 

 the exterior liquid white forthwith flow out. Then 

 turning back the same membranes this way and that 

 way in the platter (in which the egg is supposed to 

 lie), the interior and thicker white will still retain its 

 place and globose figure, being, in fact, terminated 

 by its proper membrane, which is so thin as to be 

 altogether invisible to the eye. If you cut this, the 

 second white will straightway run out and diffuse 

 itself this way and that way, and lose its round 

 figure, just as any liquor runs out of a bladder con- 

 taining it when it is cut*.'* 



We are disposed to agree with the opinion first 

 stated by Dr. Paris on the use of the white, as being 

 mainly designed to regulate temperature. " The 

 albumen, he remarks, being a most feeble conductor 

 of caloric, retards the escape of heat, prevents any 

 sudden transition of temperature, and thus averts the 

 fatal chills which occasional migrations of the parent 

 might induce. As an illustration of the use and im- 

 portance of such a structure, I may observe, that 

 those fish which retain their vitality a considerable 

 time after their removal from the water, as eels and 

 tench, have the power of secreting a slimy and viscid 

 fluid, with which they envelope their bodies. Is it 

 not extremely probable that this matter, by acting like 

 the albumen of the egg and preventing evaporation 

 from the surface of the animal and the consequent 

 change of temperature, may be the principal cause 

 of this tenacity of lite f ?" 



M. Dutrochet found that the proper membrane 



of the yolk and the chalaziferous membrane are so 



closely applied to each other that they cannot be 



* Exercit. de Gener. p. 11. 



t Linn. Trans, x. 306, 



