Table 1.

Stimulus concentrations

	Concentrations
Sucrose	0.2, 0.4, 0.6 m
Glucose	0.5, 1.0, 2.0 m
Maltose	0.2, 0.4, 0.6 m
Fructose	0.3, 0.6, 1.0 m
l-Serine	0.4, 0.6, 1.0 m
l-Threonine	0.175, 0.35, 0.7 m
NaCl	0.2, 0.4, 0.6 m