A Comparison of the Biology ofEchinus esculentusin different Habitats. Part III.

Abstract

1. Gonad examinations were made on monthly samples of Echinus esculentus from Plymouth in 1934, 1935, and 1936.2. Spawning is from February–March to May, 50% spawning occurring at a temperature of 9.2–9–7° C. compared with 7.0—7.8° C. in the Isle of Man. There was a winter drop in gonad volume one year, but not the other.3. The nature, distribution and source of the pigments in the shell are discussed, and it is shown that pigment is found in quantity in the intestine only in the summer and autumn.4. The known facts with regard to the seasons of growth, spawning, etc., are brought together into a generalized diagram.