How To Study Living Animals


The Frog’s Mouth
Materials.

Preserved or freshly killed frogs in dishes or shallow pans of water; forceps and a bristle herunterladen.

Observations.

Open the frog’s mouth as widely as possible and, if necessary, insert a splinter to hold the jaws apart. Identify the following structures:—

Tongue herunterladen.

Draw it forward until the free end extends from the mouth and is outspread; observe its form, extent, and attachment.

Teeth.

Find those on the jaws and on the roof of the mouth microsoft office kostenlos downloaden vollversion deutsch chip.

Nostrils.

Push the bristle inward through a nostril to determine its direction and extent.

Vocal cords.

These form a hard white mass in the floor of the mouth, well back behind the tongue.

Glottis,

the slit inclosed between the vocal cords, opening into the trachea.

Esophagus,

the passage to the stomach, at the posterior end of the mouth.

Eustachian tubes,

small passages outward to the ears at the junction of the upper and lower jaws.