Physiological Studies on Pupillary Reaction

1. The excitability of the different parts of the retina for the Pupillary reflex movement was examined with Hess's differential pupilloscope. 2. The consensual reaction is observed in man, cats, and dogs, but found neither in those animals whose optic fibres decussate perfectly in the chiasma,-for example, guinea-pig, nor in those animals which have non-decussate fibres not running to the superior colliculus, - for example, rabbits, rats, and goats. 3. The so-called Gudden's pupillary fibres are identical with the optic fibres themselves, but their nerve fibres are nothing but the special optic fibres which run to the superior colliculus. 4. The pupillary movement does not attend to the accomodation of the eye itself, but convergence of the visual axes. 5. A new scheme of the nervous connection for the pupillary reflex movement which explains all facts known without contradiction is advanced by the author.