microscope, and thus furnished Borelli with the anatomical grounds upon which he formulated the principles of the action of this substance, also showing that the contractions were induced through the nerves. Although much that he taught was erroneous, being entirely dominated by mechanical conceptions of the nature of muscular contractility, the refutation of his errors showed the right lines, which was possible only on the structural basis which the microscope had supplied.
The most important step towards an understanding of the nature of muscular action was taken shortly afterwards by a Fellow of this College, Francis Glisson, whose name is more generally associated with his work on the liver and on rickets. In a treatise however published by him in 1673 De natura substantiæ energetica he first explained the property of muscle substance, which he called "irritability," the character and phenomena of which were further developed by Haller nearly a century later.
Important as the work was that Malpighi did in respect to the discovery of the capillary blood vessels and the structure of the lungs, almost if not quite as great was that which he accomplished in connection with the secreting glands. In earlier times the word "gland" had a wider range of meaning and included such organs as
