EXTRAORDINARY RESULTS. 297 



paper, three thick coats of oil-paint were then added, 

 the paint consisting of white-lead with a large 

 proportion of sugar-of-lead ; this was done with 

 the double intention of offering an additional ob- 

 struction to the air, and also to prove whether the 

 paper was or was not entirely sufficient for this 

 purpose, concluding that if it were not, the vapour 

 from so noxious an application must have inevi- 

 tably prevented the process of incubation. All 

 this, however, had no effect, the egg was opened 

 at twelve and a half days, and 

 no interruption had occurred 

 to the development of the 

 chick I The anatomical pre- 

 parations illustrating these sin- 

 gular facts are to be found in 

 the museum of Guy's hospital. 

 A representation of a nineteen 

 days' chick with the egg-shell 

 covered as described, is annexed- 



The air contained in the little space at the broad 

 end of the egg is not apparently used for respira- 

 tion during the first eighteen days of incubation. 

 In what manner, therefore, this function can in 

 reality be carried on appears difficult of compre- 



