138 
too large to pass through the natural aperture. On the 
right side, the opening is usually a ragged rent in the skin, 
which has become thin at that part. The immediate con- 
sequence of the protension of the forelegs is to stop aquatic 
respiration and throw all the work of breathing on the 
lungs. The animal now remains almost constantly on the 
surface, and it very soon becomes exhausted and drowns if 
unable to support its mouth above water. The tail at this 
time rapidly shrinks, being absorbed and used as stored-up 
nutriment by the animal whilst it is unable to feed. It 
remains several days in the water in this state, but when 
the tail has been reduced to a brown stump of about half 
an inch iong, and the changes in the alimentary canal are 
completed, the animal shows an instinctive desire to climb. 
Beaching the border of the pond it will make its way up a 
steep or even perpendicular surface to the height of several 
feet, if this be necessary, in order to climb the bank. The 
remaining stump of tail serves as provision for several days 
longer, after which the young frog takes small insects as 
food. 
It must be remarked that no special value is attached to 
the exact number of days assigned to each period, for in 
strictness they apply only to the particular tadpoles 
examined. In order to make the successive periods agree 
as nearly as possible with each other, the most advanced 
tadpole was selected out of a number taken for each daily 
observation, and in consequence the periods are made rather 
shorter than the averages would have been. There was an 
interval of twenty days between the escape of the first and 
of the last frog from the water. 
