A course of elementary instruction in practical biology / by T. H. Huxley ; assisted by H. N. Martin.

  • Thomas Henry Huxley
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: A course of elementary instruction in practical biology / by T. H. Huxley ; assisted by H. N. Martin. Source: Wellcome Collection.

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    those of the pleurse and of the peritoneum in the higher animals, it is termed the pleuroperitoneal cavity; and the soft smooth membrane which lines it and covers the contained viscera is the pleuroperitoneal membrane. The vertebral column traverses the middle of the roof of this cavity, and the layer of pleuroperitoneal membrane which lines each lateral wall of the cavity, passes downwards on each side of the vertebral column and joins its fellow in the middle line to form a thin sheet, the mesentery, which suspends the alimentary canal. In the triangular interval left between these two layers before they unite, a wide canal (subvertebral lymph sinus), the dorsal aorta and the chain of sympathetic ganglia, are situated. The antero-dorsal moiety of the pleuroperitoneal cavity is occupied by the gullet, which places the mouth in com- munication with the stomach. Beneath the gullet the pleuroperitoneal cavity is separated only by a thin partition from a chamber, the pericardium, which contains the heart. The posterior face of the partition is constituted by the pleuroperitoneum, its anterior face by a membrane of similar character, the pericardial membrane, which lines the pericardium and is reflected on to the heart, in the same way as the pleuroperitoneum lines the pleuroperitoneal cavity and is reflected on to the intestine. The exposed surfaces of both the pericardial and pleuroperitoneal mem- branes are kept permanently moist by a fluid (serous fluid) which more or less completely fills the cavities which they enclose; hence they are termed serous membranes. A layer of the muscular fibres which enter into the body- wall is continued inwards at the anterior boundary of the pleuroperitoneal cavity and is attached to the sides of the oesophagus and to those of the pericardium, thus consti- tuting a so-called diaphragm; which, it will be observed, is
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