86 



Scientific Proceedings (118). 



organisms. Its advantage over that which Barber described in 

 the Philippine Journal of Science in 1914 is its simplicity of con- 

 struction, and the accuracy with which it can be manipulated. 



The apparatus consists of two instruments, the micro-manipu- 

 lator for producing movements in the microscopic field in any of 

 three dimensions and, second, the micro-injection instrument for 

 securing the necessary pressure to drive or suck substances through 

 a micro-pipette. The method of making glass micro needles and 

 pipettes is given in full in Barber's paper and in mine in the 

 Biological Bulletin of 191 8. 



The micro-manipulator is small and compact and can be 

 attached to the stage of any microscope. It consists of a system 

 of rigid metal bars connected together with spring hinges. By 

 turning certain screws the bars are forced apart. On reversing 

 the screws the springs return the bars to their original positions. 

 The instrument moves the tip of a needle or a pipette in three 

 arcs at right angles to one another. The arcs are small enough 

 so that, in the microscopic field, the needle moves practically in 

 straight lines. The movements are fine and steady enough to be 

 under perfect control when viewed under the highest power of the 

 microscope. The instrument can be used singly for one needle 

 only or with a companion when two needles, or a pipette and a 

 needle, are to be used simultaneously. 



In the micro-injection instrument mercury or an inert oil 

 (Nujol) is used to procure the necessary pressure. The instrument 

 consists of a thin-walled steel tube about six inches long and half 

 an inch in diameter, one end of which is provided with a stopcock. 

 The other end leads into a small steel tube fine enough to be 

 flexible and long enough and so bent that, while the large tube lies 

 on the table beside the microscope, the tip of the fine tube can 

 be held in the pipette carrier of the micro-manipulator. Into 

 this tip a glass Barber pipette is sealed. Mercury or oil is intro- 

 duced through the stopcock of the large tube and is forced on into 

 the micro-pipette. The stopcock is then shut off. By means of 

 leverage clamps on the thin-walled tube the mercury or oil can 

 be driven through a pipette having an aperture of only one micron 

 in diameter. By turning the screws of the micro-manipulator 

 the tip of the pipette can be brought into a hanging drop in a 



