STRUCTURE OF EGGS. 117 



having too free a communication with the atmosphere, 

 by which its powers are exhausted : it is to obviate 

 such an effect that the horticulturist, taught only by 

 experience, covers it with a glass, by which means he 

 limits the extent of its atmosphere, and consequently 

 decreases its respiration, transpiration, and the inor- 

 dinate actions which would prove fatal to it*." 



* Linn, Trans, x. 309. 



