Fig. 72. A late neurula and an early embryo of the salamander. Left: The 

 neural tube is almost completely formed and a large elevation marks the brain 

 region. The neural tube runs from right to left in the photograph. Rjgbt: An 

 elongate embryo with the head at extreme right. This is a view of the right side 

 of the embryo. The convex upper surface is the dorsal side. The tail outgrowth 

 has not yet appeared. (Courtesy Professor John A. Moore, Columbia University.) 



PRONEPHRIC 

 SWELLING 



GILL PLATE 

 NASAL PIT 



PRONEPHRIC SWELLING 



GILL PLATE 



GILL PLATE 



NASAL PIT 

 SUCKERS 



Fig. 73. Three stages in the development of the embryo of Kana sylvatica. 

 Note the progressive development of the head region and the appearance of the 

 nasal pits, the eye, the gill plate, and the mucous glands (suckers) . The embryo 

 changes in shape, becoming longer and more slender. The tail begins as a bud, 

 which elongates progressively. (Courtesy Professor Arthur W. Pollister, Colum- 

 bia University.) 



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