50 



PROTOPLASM 



Among the newer models, that of P. de Fonbrune is the most 

 ingenious (Fig. 38). It consists of a universal joint which 

 controls three pistons operating against air. By means of 

 three tubes, the pressure exerted by the pistons is conveyed 

 to a separate machine where three metal diaphragms, similar 

 to those of aneroid barometers, are forced out or drawn in 

 and thus control, by means of levers, the rod to which the 



Fig. 37. — 'The Peterfi micromauipulaiui. {From Carl Zeiss.) 



microneedle or pipette is clamped (Fig. 385). The manipulator 

 operates with remarkable precision, being wholly free from lost 

 motion. The independence of operating and receiving mecha- 

 nism eliminates vibration. Additional advantages are that the 

 hand of the operator and the needle point move in the same 

 direction and that the operator's hand need never leave the one 

 lever with which all movements are performed. De Fonbrune 

 has also constructed an instrument for automatically drawing 

 needles and pipettes under the microscope lens. 



