ABSTRACT
Spontaneous activity is a well attested characteristic of holothurian muscle (Hill, 1926; du Buy, 1936a, Wells 1942). Some preparations show regular rhythmical contractions and have been used to test pharmacological reagents (Lutz, 1930; Wyman & Lutz, 1930; Iriye & Dille, 1941), while in other preparations the spontaneous activity is so variable that this is not considered possible (Riesser, 1933 ; Bacq, 1939; Ambache & Sawaya, 1953; Welsh, 1954). For certain preparations there has been no record of spontaneous activity (Morin, 1931 ; Fischer, 1938 ; Steinbach, 1940 ; Galambos, 1941 ; Prosser, Curtis & Travis, 1951 ; Prosser, 1954; van Weel, 1955). The variations between different preparations suggest that spontaneous activity is not an inevitable property of holothurian muscle, and in fact Tao (1927) and Buddington (1937) have shown that such activity depends, in part, on the presence of intact nervous tissue. Buddington (1937) studied the cloacal breathing of Thyone, and showed that the characteristic patterns of the spontaneous contractions of isolated muscles of the cloacal complex relate to the inherent functions of each muscle in the behaviour of the animal.
