The movement in the vertical plane at right angles to the afore-mentioned movements 

 is produced by screw "I" and abuts against a vertical extension "K" of bar "C". The 

 extension "K" is parallel to the bar "J" and is connected to it at its top by means 

 of a solid spring-hinge. Turning screw "I" spreads apart bars "J" and "K", and lifts 

 the whole combination "A", "B" and "C" and imparts an arc movement in the vertical 

 plane to the tip of the needle at "D". To procure a vertical movement, the tip of the 

 needle at "D" must lie in the same horizontal plane "L" - "D" with the spring fasten- 

 ing "K" and "J" together. '.Then screw "I" is turned, the needle tip will then move in 

 an arc "I" to "Z" more nearly vertical than :m" -■t'r.^r arc on the same circumference 

 of which the point "D" is the center. 



Pick up the right hand instrument, and carefully keeping in mind the description of 

 the structure and working principle just read, turn each screw (G, H, and I) clock- 

 wise until the bars are engaged, and tlightly separated. NEVER FORCE THE BARS APART 

 TO THE LIMIT OF THEIR MOVEMENTS. THIS PUTS UNDUE STRAIN ON THE SPRING-HINGE, AND IN 

 TIME WILL TEND TO WAR? THEM PERMANENTLY. ALWAYS RELEASE ANY TENSION WHEN THROUGH 

 MANIPULATING. 



Note that in addition to the parts already described the unit has also a clamp (Gl) 

 into which may be fastened the metal holder (adapter) for micropipette or micro- 

 needle. You have already moved this clamp vertically by turning screw "I". This gives 

 the finest vertical movement of which the instrument is capable. Two other ways of 

 moving the clamp are possible. First, a coarse vertical movement may be imparted to 

 it by turning the screw "T.S.", y/hich is located on the inner side of the bars, attached 

 to. a square frame. Turn this screw and note the relative magnitude of motion. 



Finally by loosening the small screw which is at the base of this clamp, the clamp 

 may be rotated freely from side to side, or may be moved up and down in its socket. 

 This is the coarsest and most rapid way of adjusting the position and height of the 

 micropipette and needle. It is used to adjust the height of the carrier for differ- 

 ent sized chambers. When once adjusted it is not used further. The carrier may be 

 rotated without changing its vertical height. 



Pick up the left hand instrument. Note that the three screws must also be turned 

 clockwise to engage the bars. Do not attempt at present to mount these instruments. 

 Instructions for mounting them on the metal base are given in a later section. 



Choice of Microscope and Microscope Accessories 



MICROSCOPE STAND . Any good compound microscope may be used if it meets the following 

 requirements. First, due to the fact that a special condenser must be used, the open- 

 ing in the microscope stage must be large enough to allow the top of the split con- 

 denser to be flush with the surface of the stage. Second, the mechanical stage must 

 have sufficient size and range to accommodate a moist chamber (fig. 2, x) constructed 

 on a 2" by 3" base and allow of its being moved back so that the cover slip roofing 

 the moist chamber completely clears the condenser lens. To insure this, it is advis- 

 able to use a microscope with a handle curved outward. This permits the rocking back 

 of the moist chamber to a greater distance so that this clearance of the condenser 

 lens is possible. 



MOIST CHAMBER. The moist chamber (fig. 2, x) just mentioned is constructed as follows; 



