However, in the example of FIGS 4 6, the pump 53 is operable to perform the discharge and suction of fluid separately in {HEAD ~ the fluid channel} 44 of the first layer and the fluid channel 54 of {TAIL ~ the second layer} 
However , in the example of FIGS 4 6 , the pump 53 is operable to perform the discharge and suction of fluid separately in { HEAD ~ the fluid channel } 44 of the first layer and the fluid channel 54 of { TAIL ~ the second layer }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL