Landacre, Taste Buds of Aineiiirus. II 



layer of the epidermis, while the taste buds always begin as an 

 evagination of the same layers. On the outer surface the same 

 distinction exists between the taste buds and the neuromasts. 

 All neuromasts are in the form of more or less well defined de- 

 pressions of the epidermis at the time taste buds appear, while 

 the taste buds, as in the mouth and pharynx, begin as elevations. 

 Even in cases where the neuromast does not begin as a well de- 

 fined depression, the presence of two layers of cells, the outer one 

 of which is rounded and lies quite near the surface and will later 

 become the pear shaped sensory cell so characteristic of neuro- 

 masts, makes the separation of these two types of organs easy. 



In order to avoid any possibility of confusion all the lateral 

 line organs of all the series in which taste buds occur and all the 

 neuromasts present in the earlier stages have been located, and 

 at the time the first taste buds appear all the placodes of the lateral 

 line organs are present and accounted for. 



In this connection it may be of interest to note the difference 

 in time of maturing of these two types of organs. Perfectly formed 

 lateral line organs with the sensory cells having the same shape 

 as in the adult and with their free borders exposed can be found 

 as early as series N, 138 hours. This is about the time of 

 hatching and is probably correlated with the effort of the young 

 fish to right and orient themselves, which occurs about this time, 

 although no notes were taken of the exact time when this occurs; 

 nor were any notes taken of the exact time at which the young 

 orient themselves in the nest after they can maintain an erect 

 position. This orientation is quite a characteristic phenomenon 

 of larvae of very young cat fish, however. 



On the other hand, no taste buds are found in my series that 

 could be considered mature until much later, probably in series 

 Q, 174 hours. It is much more difficult to determine when taste 

 buds mature on account of the irregularity in the staining of the 

 sensory cells in the taste buds. There are, however, in series O, 

 both in the oral cavity and in the pharynx, buds that resemble 

 mature buds of the oldest embryo studied in all essential details 

 except size. The later maturing of the taste buds is probably 

 correlated with the reduction in amount of yolk and the begin- 

 ning- of feeding; on food secured from the surrounding; water. 



As to the relative time of maturing, there is no apparent dif- 

 ference between the oral, pharyngeal and cutaneous regions. Ma- 



