NOTE VIII., CHAPTER II., p. 81. ANAL RESPIRATION IN CRAYFISH.

NOTE VIII., CHAPTER II., p. 81. ANAL RESPIRATION IN CRAYFISH.

Lereboullet (“Note sur une respiration anale observée chez plusieurs Crustacés;” Mémoires de la Société d’Histoire Naturelle de Strasbourg, IV. 1850) has drawn attention to what he terms “anal respiration” in young crayfish, in which he observed water to be alternately taken into and expelled from the rectum fifteen to seventeen times in a minute. I have never been able to observe anything of this kind in the uninjured adult animal, but if the thoracic ganglia are destroyed, a regular rhythmical dilatation and closing of the anal end of the rectum at once sets in, and goes on as long as the hindermost ganglia of the abdomen retain their integrity. I am much disposed to imagine that the rhythmical movement is inhibited, when the uninjured crayfish is held in such a position that the vent can be examined.