By adding one more second order tubes to the XOR gate (Fig. 3a–
d) we produce a gate with two inputs and two outputs (Fig. 3e–h).
The gate is shown in (Fig. 3e–h). It computes exclusive disjunction
and negated disjunction in parallel. The output tube z = x y acts
in a manner similar to an XOR gate (Fig. 3a–d). The output tube
p ¼ x þ y connects the inlet to tube x, just before the junction of x
and z, to the outlet of the junction of the tubes x and y. Cytoplasmic
flow is directed via tube p, p = 1 only if tubes x and y are
blocked, x = 0 and y = 0 (Fig. 3h).