Observations upon the Behaviour and Structure of Hydra.

Abstract

ABSTRACT The Hydras upon which the following observations were made were obtained from various sources, chiefly through the kindness of Dr. Monica Taylor, from the Convent of Notre-Dame. They were kept in covered, half-pint glass tumblers, in water from a large tank in which there was a fair quantity of weed and a variety of animal life (Isopods, Cladocerans, Planarians, &c.). This was used because the Hydra would not live for more than one or two days in tap-water. The water was-changed and the tumblers cleaned when necessary. This was about once a week in summer, as food-remains became foul very quickly then, but less frequently in winter. The water was never aerated artificially. The Hydras were fed on a culture of Daphnia twice a week, and the remains and excreta removed, as far as possible, the following day. Under these conditions the Hydras lived and remained healthy for months. Occasionally one or two, for no apparent reason, would decrease in size and finally degenerate and die, but in only one case was a whole tumbler attacked by a ‘depression period Even here a fair proportion remained healthy throughout. When well fed the Hydras budded actively. None of my specimens carried more than four or five buds at a time and the number was usually less.