Temperature control apparatus used in flagellar regeneration experiments

Figure 38 illustrates diagrammatically the type of apparatus used to control temperature in the regeneration experiments of §V. The centrifuge box on the left of the diagram is used for the separation of cell bodies subsequent to deflagellation outside. The centrifuge is a variable speed type capable of a maximum 1600 rev/min. Thermal insulation is provided by a 3 in. thickness of expanded polystyrene. The temperature of this box is only roughly controlled to approximately 1 °C by means of a refrigerator probe and hot air blower. Both heating and cooling elements are under the control of mercury contact thermometers. The deflagellated organisms and the undeflagellated controls are placed in specimen tubes mounted on a rack in the right-hand chamber built from copper sheet and insulated in the same manner as chamber 1. Cooling or heating of this container is carried out by four thermo-electric units which are controlled by a thermistor temperature regulating system. The transparent top cover of the box allows the light from a 22 W fluorescent tube to illuminate the specimen area, and is also provided with small orifices through which specimen samples may be taken. The thermal conditions inside the growth compartment, recorded over 12 h continuous operation, showed temperature differentials, of the order of 0·05 °C, and within the specimen tube, better than 0·01 °C.