214 THE FROG CHAP, xn * 



mentation cavity and archenteron, and the development of the central 

 nervous system and notochord (Figs. 64, I, K, and 65) ; and directions 

 for the study of the development of the chief organs of the chick will be 

 given in a subsequent chapter. But if you wish to make the attempt, 

 proceed as follows : 



Take a few eggs every day from the time they are laid until the 

 tadpoles are hatched : place these on a tile or piece of glass, and with a 

 pair of needles dissect off the gelatinous covering. Then carefully transfer 

 the segmenting eggs or embryos into corrosive sublimate for a quarter 

 to half an hour, and after washing in running water, put them into 

 weak and then strong alcohol ; stain, imbed, and cut sections as 

 directed on p. 136. 



