COL UR OF EGGS. 23 



pellicle ; this makes the shell weaker. "When the spe- 

 cimens are quite clean internally, and have become 

 dry (which will be in a day or two), take the syringe 

 and inject them with a strong solution of isinglass 

 (with a little sugar-candy added to prevent its crack- 

 ing) ; blow this out again whilst warm. Let the shell 

 get dry, and then wash the outside with a soft wet 

 cloth to remove saline particles, dirt from the nest, 

 &c. This method varnishes the inside, and the first 

 specimen on which it has been tried was the before- 

 mentioned hedge-accentor's egg, which is to this day 

 as bright in colour as a fresh specimen. 



Also in a pair of nightjar's eggs, of which species 

 the delicate grey tint is particularly evanescent, one 

 was injected in the manner described, and the other 

 was not ; in the first the grey is still perfectly defined, 

 in the other it has entirely disappeared. Eggs which 

 have lost their internal pellicle become strengthened 

 by this process, and those which have not lost their 

 colour greatly improved. 



