This form is so similar to Obelia that one cannot differentiate between the two, using the anatomy of the feeding individuals as the sole criterion. Even the gonosomes are similar in the two genera, each consisting of a transparent gonotheca with the blastostyle extending from base to tip, and the gonophores budding from it. The gonophores of Campanularia are very degenerate, however, and their medusa-like structure can be distinguished only in sections. Because the gonophores are so inconspicuous and the embryos so obvious, the colonies which produce female gonophores and which later contain embryos are loosely spoken of as "female" colonies, although actually they are asexual.

The colonies are very abundant on floating sea-weed and timbers in shallow water.

BREEDING SEASON.: June and July.

A. Care of Adults: The colonies can be kept in large dishes or beakers supplied with sea water.

B. Methods of Observation: The eggs and planulae may be studied either by mounting a gonosome in sea water on a slide, or by dissecting the embryos from the gonophores with fine needles. The mature planulae will metamorphose readily if two or three are placed in a covered Syracuse dish of sea water. Once the planulae attach, the water in the dish should be changed at least twice a day.

NORMAL DEVELOPMENT

A. Asexual Reproduction: The gonosomes of a female colony are larger than those of the male, and contain a series of embryos which are budded off from the blastostyle in a regular order, so that the older buds are closer to the mouth of the gonotheca. A single egg or embryo develops in each gonophore. The smaller, oval, male gonosomes resemble those of the female, and bear rounded gonophores filled with milky-gray sperm which become active when they are discharged into sea water.

Details of gonophore development may be found in the paper of Goette (1907).

B. Sexual Reproduction: The maturation and development of the eggs have been studied by Hargitt (1913). There are no nurse cells present; a conspicuous release of chromidia from the nucleus occurs during the maturation process. The large, irregularly-shaped eggs (approximately 160 microns in diameter) are fertilized in situ, cleave, form a morula, gastrulate by delamination, and reach a free-swimming planula stage within the gonophores. Mature planulae are two or three times longer than they are broad, and show maggot-like movements while they are still within the gonotheca.

C. Later Stages of Development and Metamorphosis: Four to ten hours after leaving the gonotheca, the mature planulae will attach. Each then opens a mouth, puts forth tentacles, secretes a hydrotheca and perisarc, and becomes a fully-formed individual polyp in two or three days.

BERRILL, N. J., 1950. Growth and form in calyptoblastic hydroids. II. Polymorphism within the Campanularidae. J. Morph., 87: 1-26.

GOETTE, A., 1907. Vergleichende Entwicklungsgeschichte der Geschlechtsindividuen der Hydropolypen. Zeitschr.. f. wiss.. Zool., 87: 1-336.

HARGITT, G. T., 1913. Germ cells of coelenterates. I. Campa'$ularia flexuosa. J. Morph., 24: 383-413.

HARGITT, G. T., 1919. Germ cells of coelenterates. VI. General considerations, discussion, conclusions. J. Morph., 33: 1-58.