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close. The external gills attain their full size on the second 
day, after which they gradually shrink, but continue in 
action about a week, soon after which what remains of them 
disappears within the opercular fold. The organs which are 
developed during this period are all completed at about the 
same time, that is, very nearly at its close. The eyes and 
nostrils progress regularly from the time of hatching, but 
with regard to the internal gills and the alimentary canal, 
it appears that the former are commenced first and are 
probably in use about the fifth or sixth day in conjunction 
with the external gills, gradually increasing in efficiency as 
the latter diminish in size, but the complete apparatus for 
the tadpole respiration is not perfected until the opercular 
fold has joined the skin of the abdomen, leaving only a 
small opening at the left side, and until, in conjunction with 
the chambers thus formed, the nasal passages are opened 
into the back of the mouth. The development of the 
peculiar tadpole mouth and the enlargement of the abdomen, 
indicating the formation of the coiled intestine, commences 
only when the gill-chambers are complete, and these struc- 
tures are formed and brought into use within the last 
three days of the period ; during which time also the tadpole 
becomes beautiful with spangles exactly resembling bits of 
gold leaf embedded in the rich brown transparent skin. 
