The physiological significance of important regions of the body was shrouded in darkness. No need to mention the vermiform appendix, which was a mystery; in rabbits it was regularly found full of a pulpy substance, of which there was nothing to say as to how it got in or renewed itself. But what about the white and grey substance which composed the medulla, what of the optic thalamus and the grey inlay of the

pons Varolii ? The substance composing the brain and marrow was so subject to disintegration, there was no hope whatever of determining its structure. What was it relieved the cortex of activity during slumber?