SPERM AGGLUTINATION IN THE KEYHOLE LIMPET, MEGATHURA CRENULATA

¹ From the William G. Kerckhoff Laboratories of the Biological Sciences, California Institute of Technology, Pasadena

1. Egg water of the keyhole limpet, Megathura crenulata, causes a strong agglutination of the sperm of this species. In contrast to the rapid spontaneous reversal that occurs in the sea urchin, the reaction here is relatively irreversible, the agglutinates persisting in most cases until after the death of the sperm. Spontaneous reversal occurs when an excess of sperm is employed.

2. When anti-agglutinin (sperm extract) is added to agglutinin (egg water) the latter is immediately neutralized and a precipitate later appears. The precipitate appears very much later with the keyhole limpet substances than with those of the sea urchin, the time corresponding roughly to that at which reversal of agglutination occurs in these two forms.

3. With varying concentrations of agglutinin and sperm suspension the occurrence and rate of agglutination behaves in a manner similar to that described as the zone phenomena in serological reactions.

4. The sperm agglutinate by their tails and under certain conditions by their heads as well. But the evidence shows only tail agglutinin to be present in the egg water, the head clumping being ascribed to the aggregation reaction which the sperm exhibit on dilution with sea water. The aggregation reaction is considered as an auto-agglutination and a new interpretation for this is offered based on the partial dissociation of a substance from surface of the sperm head as a result of change in pH or other conditions.

5. The agglutinin is shown to be a component of the jelly layer of the egg. No evidence of its continuous production by the egg was obtained in the sea urchin or in the keyhole limpet.

6. Although the reaction bears a superficial resemblance to what has been described as hetero-agglutination, it is found to exhibit both tissue and species specificity.

7. The agglutinates have the form and behavior of liquid drops. It is suggested that this is due to the agglutinin forming an insoluble liquid upon reaction with the spermatozoa.