[Functional change in the type of response of retinal ganglion cell receptive fields]

27% of 270 receptive fields of the ganglionic cells did not change their firing on alteration of intensity, duration or colour of the stimulus or general adaptation background. These "pure" off-receptive fields constituted the 4th group. The majority of the receptive fields, however, changed their type of firing on alteration of the stimulus parameters, and some of the fields revealed all three classes of responses: on-, on-off and off-. Three groups of receptive fields were distinguished on the ground of common regularities of functional readjustments. These findings render the Hertline classes overlapping and show the correctness of classification to depend on the experimental conditions.