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With its remarkable double-S shape, IC 4634 is an archetype of point-symmetric planetary nebulae (PNe). In this paper, we present a detailed study of this PN using archival HST WFPC2 and ground-based narrowband images to investigate its morphology, and long-slit spectroscopic observations to determine its kinematics and to derive its physical conditions and excitation. The data reveal new structural components, including a distant string of knots distributed along an arclike feature 40 ''-60 '' from the center of the nebula, a skin of enhanced [O III]/Ha ratio enveloping the inner shell and the double-S feature, and a triple-shell structure. The spatio-kinematical study also finds an equatorial component of the main nebula that is kinematically independent of the bright inner S-shaped arc. We have investigated in detail the bow shock-like features in IC 4634 and found that their morphological, kinematical, and emission properties are consistent with the interaction of a collimated outflow with surrounding material. Indeed, the morphology and kinematics of some of these features can be interpreted using a three-dimensional numerical simulation of a collimated outflow precessing at a moderate, time-dependent velocity. Apparently, IC 4634 has experienced several episodes of point-symmetric ejections oriented in different directions, with the outer S-shaped feature being related to an earlier point-symmetric ejection, and the outermost arclike string of knots being the relic of a still much earlier point-symmetric ejection. There is tantalizing evidence that the action of these collimated outflows has also taken part in the shaping of the innermost shell and inner S-shaped arc of IC 4634.

Based on optical and near-infrared ground-based spectroscopy and optical and near-infrared Hubble Space Telescope (HST) images, we confirm the classification of Hen 401 as a bipolar proto-planetary nebula. HST images reveal a highly elongated morphology, consisting of two main bipolar lobes of unequal surface brightness separated by a dark lane of dust with a total extension of 28'' x 3'', superimposed on a much fainter background emission of elliptical shape extending over ~10'' x 5''. The simultaneous detection of spectral lines formed under very different density conditions, together with the strong obscuration observed along the equatorial plane, is interpreted as the signature of a circumstellar disk, which would be responsible for the strong collimation observed. We conclude that the emission observed is mainly due to scattering of the light originated in the fluorescence-excited inner region of the circumstellar disk. In addition, we also report the detection of strong molecular H2 emission in the near infrared, confirming that the onset of the H2 emission occurs in proto-PNs after the bipolar structure has developed, but before photoionization takes place.