Page:The Harveian Oration,1902.djvu/17

 called 'natural'. . . Many animals are endowed with both sense and motion without having a common sensorium or brain, such as earth-worms, caterpillars of various kinds, chrysalides, &c. So also do certain natural actions take place in the embryo, and even in ourselves, without the agency of the brain.

But he looked upon all these natural," visceral, or reflex, actions as proceeding from the pouter of the heart and dependent on it, while the animal motions alone necessitated the controlling influence of the brain. During Harvey's lifetime, however, Thomas Willis was laying the foundations of a more exact neuro-physiology. His work on the descriptive anatomy of the brain, the arrangements of its blood-vessels, the distribution of the cranial nerves, and the relations of the vagus and intercostal, or sympathetic nerves to the thoracic and abdominal viscera contains much of enduring value. Amid much fanciful speculation as to the functions of the different parts of the brain and the nature of the animal spirits, he came near formulating a true con-