MICRURGY 49 



capillary attraction of the pipette or by suction produced by a 

 bulb or syringe attached to it. The cover of the moist chamber 

 is now replaced by another containing pure culture medium 

 into which the single isolated bacterium is ejected from the 

 pipette. 



Barber occasionally substituted a needle for the pipette 

 and indulged in some simple experiments in dissection, such 

 as pulling an amoeba apart. He thus saw the possibilities 

 of his instrument for microdissection. It was, however. Kite 

 who converted the Barber pipette holder into a microdissector 

 and used it for this purpose. In so doing, he inaugurated a 

 new method of microscopical technique, which, chiefly in the 

 hands of Chambers in America and Peterfi in Germany has 

 done much and promises more toward an understanding of 

 the anatomy and physiology of cells. To this new field of 

 biological endeavor Peterfi gave the name Mikrurgie (micro, 

 small; ergon, work). 



Types of Instruments. — With the statement that several 

 other less well-known instruments have been made, we can 

 limit ourselves to six types of micromanipulators, the two 

 original ones of Schouten and Barber and the four later models 

 of Chambers, Peterfi, Taylor, and de Fonbrune. 



Kite modified the Barber pipette holder by joining two 

 holders so as to form one double instrument (Fig. 35), which he 

 attached directly to the stage of the microscope. 



The chief fault of the Barber-Kite instrument was loose 

 play (lost motion) in the threads and consequent lack of rigidity. 

 Great precision in movement is most essential when dissecting 

 under the highest power of the microscope. To overcome this 

 defect Chambers designed an instrument based on principles 

 somewhat similar to those of Schouten. Heavy steel springs 

 are banded together at one end and forced apart by thumb- 

 screws at the other end. The springs are fastened to an upright 

 piUar. Movement of the needle is obtained by forcing the 

 springs apart. 



The Peterfi (Fig. 37) micromanipulator is of excellent con- 

 struction, and the Taylor model a very solid instrument. Both 

 have the great advantage of freedom and extent of movement. 

 The needles can be inserted in their holders away from the moist 

 chamber and then brought into position with mechanical control. 



