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the close of the period both pairs are well grown, and 
the shoulder girdle and pelvis are developed. The lungs at 
the same time have attained a considerable size, and are in 
the form of a pair of sacculated tubes bluntly pointed at 
their free end. 
The fifth and last period of the aquatic life of the frog 
extends from the seventy-fourth to the eighty-third day, 
at which time the animal has left the water and attained 
the perfect form of the adult. At the commencement of 
this period it is a tadpole with a large tail, a pair of large 
hind legs with webbed feet, and a pair of equally well 
developed fore legs still retained within the gill-chamber. 
The gills continue in action, and the opening at the left side 
remains for the discharge of water. But now remarkable 
changes rapidly take place The animal ceases entirely to 
feed, and the alimentary canal soon becomes empty, the 
large white frilled lips shrink, and the sets of small teeth 
upon them degenerate and drop off, the horny beaks 
disappear, the mouth widens, the lips consist of ordinary 
skin, and the large fleshy bifurcated tongue of the frog is 
formed. At the same time, the intestine shrinks both in 
length and diameter, especially at the part which forms the 
centre of the coil; soon afterwards its upper part begins to 
be dilated to form the stomach, and the remainder becomes 
rapidly smaller and shorter as the stomach enlarges, until it 
consists of a small and slender gut, making only two or 
three short turns below the stomach at the left side. The 
liver at the same time enlarges, and the gall-bladder is seen, 
very large and filled with dark green bile. 
When these changes in the alimentary apparatus have 
been partly accomplished, the forelegs are pushed out, the 
action being instantaneous for each limb, sometimes the 
right, sometimes the left comes out first, and the left limb 
is always forced through the gill-opening, the margin of 
which is torn in consequence of the size of the limb being 
