Iodine Compounds and Fertilisation

Abstract

ABSTRACT If fresh and ripe spermatozoa of E. esculentus or E. miliaris are put into a solution of thyroxine in sea-water of a concentration of 1/50,000 by weight and at the hydrogen-ion concentration of sea-water (pH 8-2), they very soon come together by their heads and form clumps. The most favourable concentration of the sperm for observing this phenomenon is a mixture of sea-water and undiluted sperm in a proportion of 500 : 1 or 1000 : 1. This “agglutination” is visible under the microscope in 1-3 min. and becomes very obvious in 10 min. In a short time the larger clumps fall to the bottom and there form a flocculent precipitate, which can be collected into the centre of the dish by shaking, and is easily visible to the naked eye. The clumps are dense and at first spherical, but their shape becomes irregular as they grow larger, probably in part by the coalescence of several small clumps to form one larger one, and in part by uneven addition of spermatozoa on the outside of the clump. The sperm are active, at least for many minutes, after they are agglutinated. The agglutination is permanent. It only occurs in fresh and ripe sperm. Perfectly ripe sperm may show a slight spontaneous agglutination in seawater, but this is always much less than the agglutination in the presence of thyroxine.