Physiological Reactions of Goldfish with Severed Spinal Cord.

Abstract

So far as the writer is aware, the work of Koppányi and Weiss, 1 and Pearcy and Koppányi 2 on goldfish, and that of Nicholas 3 on Fundulus embryos (none of which has been published in full), constitute all that has been done on spinal cord section in teleosts. The first two of these papers report functional regeneration of the severed cord. Nicholas definitely failed to secure any restoration of function or of anatomical continuity.

To further test the matter, a study of the results of spinal section in the goldfish (Carassius auratus) has been undertaken. To date, 25 small goldfish have been subjected to operation on the spinal cord. The animals were anesthetized with chloretone, transluminated in a dark room, and the spinal cord presumably cut with a knife in the region marked by the beginning of the dorsal fin. Subsequent histological examination has proved cord section in the majority of these.

Koppányi and his coworkers state that all goldfish in which the spinal cord has been severed lie on their sides. This was not found to be true in this investigation. Some remained erect, while others lay on their sides when at rest. All were capable of swimming voluntarily. As some specimens which lay on the side did not have sectioned cords, spinal section is not the cause of this behavior. The nature of the injury producing this posture is, as yet, unknown, though experiments to determine it have been carried out.

Light tactile stimulation on the body fails to produce any response in the normal, or in the spinal fish if applied cephalad to the lesion. Stronger stimulation causes swimming in normals and, if applied in front of the lesion, in spinal fish.