CRANIAL GANGLIA OF AMBLYSTOMA 



455 



cells at this stage and its large characteristic mesodermal yolk 

 gramiles (fig. 37), which are retained for a long time, make a 

 sharp contrast with the other branchial cartilages, which now 

 contain practically no yolk granules. 



Stage 46 + 



Lateral-line groups of sense organs. The subsequent growth of 

 the lateral-line primordia is merely a matter of the development 



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37 



Fig. 37 Frontal section at the level of first basibranchium, showing at stage 

 42 formation of second basibranchium from mesoderm near anterior wall of peri- 

 cardial chamber. X 250. 



of sense organs out of the ectodermal thickenings as they are laid 

 down in stage 37-38 (fig. 10). 



The general distribution of the lateral-line sense organs has 

 been described in a number of amphibians. Descriptive figures 

 are shown by Kingsbury ('95) of the distribution of different 

 groups of sense organs connected with the lateral-line system in 

 eight groups of amphibians. However, two figures (figs. 11 and 12) 

 have been included in this paper to show the groups of sense 

 organs developed from the primordia of stage 37-38 as they are 

 finally laid down in a 13|-mm. larva of Amblystoma punctatum. 



