382 
Transactions of the Society. 
The moist chamber is open at one end to permit the entrance 
of the micro- needles or pipettes. To prevent undue evaporation, 
especially when a preparation is to be left overnight, the open end 
may be temporarily closed by means of a paraffined, thin cardboard 
trough of a shape in fig. 4. The trough is placed over the shanks 
of the needles and filled with soft vaseline containing a few threads 
of cotton to give substance to the vaseline. The vaseline closes 
around the shafts of the needle and seals the opening of the chamber 
Fig. 5. — Method of making the needles, h, position of hands 
when making needles over micro-burner ; a, glass tube with capillary ; 
b, needle with tip bent up ; c, a good needle tip ; d, needle tip 
serviceable for converting into a pipette ; e, unserviceable tip drawn 
out into a hair ; /, needle with stout shank ; g , needle with tip bent 
back for cutting purposes. 
without interfering with the movement of the needles. To prevent 
the vaseline from spreading on the floor of the moist chamber it is 
well to have a shallow pan of cardboard set under the shanks of 
the needles for the trough to rest upon. 
The needles are made either from soft or hard glass tubing. 
If a brass tube is to be used to serve as a guide for the in and out 
movement (cf. fig. 3 1 ) the glass tubing should be selected to fit the 
tube. What I use is a fraction less than J in. in outside diameter. 
