M. GIBBS and E. LATZKO In the preface to his Experiments upon Vegetables, INGEN-Housz wrote in 1779: "The discovery of Dr. PRIESTLEY that plants have a power of correcting bad air . . . shows . . . that the air, spoiled and rendered noxious to animals by their breath ing in it, serves to plants as a kind of nourishment. " INGEN-Housz then described his own experiments in which he established that plants absorb this "nourishment" more actively in brighter sunlight. By the turn of the eighteenth century, the "nourishment" was recognized to be CO . Photosynthetic CO2 assimilation, the 2 major...

All animals show longlasting changes in behaviour as a result of individual experience and this adaptability is one of their most striking features. The changes may be abrupt, radical and permanent. In higher animals it seems reasonable to ascribe their ability to change behaviour to the same physiological process that underlies human behavioural change and memory. The known physiology of the brain gives no clues as to the mechanism. On the contrary, physiological research on the nervous system has relied upon the fact that the reactions of nerve cells studied were stereotyped and could be...