s of the body in health
and disease. His classification of tissues was macroscopical and
physiological; he relied upon texture and function in distinguishing
them rather than upon microscopical structure. The tissues he
distinguished are as follows:--[38]

1. The cellular membrane.
2. Nerves of animal life.
3. Nerves of organic life.
4. Arteries.
5. Veins.
6. Exhalants.
7. Absorbents and glands.
8. Bones.
9. Medulla.
10. Cartilage.
11. Fibrous tissue.
12. Fibro-cartilage.
13. Muscles of organic life.
14. Muscles of animal life.
15. Mucous membrane.
16. Serous membrane.
17. Synovial membrane.
18. The Glands.
19. The Dermis.
20. Epidermis.
21. Cutis.

The "cellular membrane" seems to mean undifferentiated connective
tissue; "exhalants" are imperceptible tubes arising from the
capillaries and secreting fat, serum, marrow, etc.; the "absorbents
and glands" are the lymphatics and the lymphatic glands.

In Bichat's eyes this resolution of the organism into tissues had a
deeper significance than any separation into organs, for to each
tissue must be attributed a _vie propre_, an individual and peculiar
life. "When we study a function we must consider the complicated organ
which performs it in a general way; but if we would be instructed in
the properties and life of that organ we must absolutely resolve it
into its constituent parts."[39] The tissues have, too, a great
importance for pathology, for diseases are often diseases of tissues
rather than of organs.[40]

[9] _Le Monde vegetal_, p. 41, Paris, 1907.

[10] _Exercitationes de generatione animalium_,1651. For
an account of Harvey's work on generation and
development, see Em. Radl's masterly _Geschichte der
biologischen Theorien_, i., pp. 31-8, Leipzig, 1905.

[11] The passage runs:--"Sic natura perfecta et divina
nihil faciens frustra, nec quipiam animali cor addidit,
ubi non erat opus, neque priusquam esset ejus usus,
fecit; sed iisdem gradibus in formatione cujuscumque
animalis, transiens per omnium animalium constitutiones
(ut ita dicam) ovum, vermem, foetum, perfectionem in
singulis acquirit."

[12] See I. Geoffroy St Hilaire, _Essais de Zoologie
generale_, p. 71, Paris, 1841.

[13] M. Foster, _Lectures on the History of Physiology_,
Cambridge, p. 53, 1901.

[14] _Zootomia democritea_, Nuremberg, 1645;
_Antiperipatias, seu de respiratione piscium_,
Amsterdam, 1661.