The Limit Between Eectoderm and Entoderm. 63 
is no relation between the taste bud and the ectoderm. At B is a 
maxillary tooth and a taste bud just behind it. At C is a taste 
bud which stands just behind the mandibular teeth. Note the yolk 
granules in both of these, although the yolk is beginning to be 
absorbed from the entoderm at this time. These are the most 
anterior taste buds found in Amblystoma and none are found on the 
Fic. 21. A. punctatum, buds and neuromast. A, taste bud near the yvomer- 
ine teeth in a stage later than Fig. 20. B, taste bud just behind the maxillary 
teeth. C, taste bud behind the mandibular teeth. D, a neuromast from the 
snout. Iron hzmatoxylin, fuchsin. 
outer surface of the head. At D in the figure is shown one of the 
lateral line organs from the dorsal surface of the snout. Note the 
pear-shaped sense cells reaching only half the depth of the epidermis. 
By the stage represented by this figure taste buds have made their 
appearance in all regions in which they are found in the adult. Up 
to this time all the territory in which taste buds appear is lined with 
entoderm only and the cells of the taste buds themselves are simply 
re-arranged entoderm cells containing yolk granules. All these points 
