TADPOLES OF XENOPUS 
life in the pond wave. Their hind feet are most obtru- 
sively webbed, and along the sides of the body are a 
row /of what look like rather careless stitches ; the baggy 
and ill-fitting appearance of the frog suggests an amateur 
attempt at repair. These stitches are in reality the 
organs of the lateral line, a structure found in the lower 
amphibia and in fishes, a sense organ probably of 
the nature of touch. The absent tongue is also ap- 
parently to be looked upon as the result of an aquatic 
life, where food slips into the mouth and is not 
manceuvred thereto} by the prehensile organ of the 
buccal cavity. The lungs are assisted in their contrac- 
tions by a very complicated system of muscles, as are 
those of Pipa. This is exactly analogous to the in- 
creased diaphragm in whales and in other aquatic 
mammals, and is a very remarkable instance of how 
Nature attains to the same result without the manu- 
facture of a special organ. A new one is simply made 
use of, and, if need be, increased and altered. An im- 
perfect representative of the Xenopine and Pipine 
“diaphragm ” exists in Rana. There is nothing pecu- 
liar in the breeding habits of Xenopus, such as occurs in 
its ally Pipa. It lays eggs in the ordinary amphibian 
way, and therefrom emerge tadpoles. These tadpoles 
are quite as interesting in their way as are their parents. 
Some few years back there were swarms of them at the 
Zoo, a pair of the frogs recently brought back from 
Zanzibar having laid eggs. They have not bred since, 
but there is always the chance of their doing so. The 
home-bred tadpole is familiar enough to everyone by 
its imp-like aspect and alluring wrigglings. The tadpole 
of Xenopus is about as different as it can be and yet 
remain a tadpole. It is clear and glassy in colour, with 
only a faint amount of pigment here and there ; and it 
has a fascinating way of standing upon its head at the 
bottom of the tank and wriggling its tail violently. 
292 
