ABSTRACT
The octopus is an exceptionally strong, active and manipulative animal. The structure of the arms enables the animal to move over any sort of terrain, to apply a formidable grip or pull, to make most delicate movements, such as picking at tight knots in wet cotton until they loosen, to reach and clean any part of the body, or to make delicate sensory discriminations. The great learning ability of Octopus was first shown for visual problems by Young and Boycott and their school, but Wells and Wells have subsequently shown an equal ability to deal with tactile information from the arms (see Wells (1962) for reviews). The arms contain a large part of the central nervous tissue of the animal, with intrinsic sensory, interneural and motor elements, possess organized reflex systems, and are capable of quite a lot of autonomy. It is thus good material in which to study the lower organization of an invertebrate central nervous system.
Slight discrepancies between the results of ten Cate and those presented in this paper are probably due to the different experimental conditions. It is to be expected that the intact, though blind, animal, at rest in its tank and gently stimulated via its own sense organs will give more complex responses than the amputated arm directly stimulated with electrical current. It is encouraging that the results are in fact so similar.
This account frequently mentions effects which spread distally but not proximally. I believe that the majority of these represent real differences in the physiological organization" but it must be remembered that the proximal regions are nearer to the site of amputation. This may influence the results.
