132 ROBERT CHAMBERS. 



greater than .05 mm. Therefore, if the dissection requires a 

 comparatively stiff shank for the dissecting needle, start with a 

 glass tube possessing a thick capillary and draw out the tip into 

 a thinner capillary. This thinner capillary may then be used 

 for making the needle point (Fig. 6, g). 



The facility in making the needle-points over the microburner 

 increases, of course, with practice. In my case, I make at times 

 twenty or thirty within an hour, at other times none, or only one 

 or two at the most. A supply may be kept on hand on a stand 

 made of two horizontal layers of wire netting, the meshes of 

 which admit the base of the needles. It is well to mark off the 

 stand into compartments to receive the various types of needles 

 that are made. 



Another good method for making the needle points is that of 

 Chabry ('87). The tip of a capillary pipette is brought into 

 contact with a heated mass of glass (or any incandescent body 

 to which glass will adhere) and suddenly drawn away. For an 

 incandescent body Chabry used the blade of a platinum knife of 

 a surgical instrument for thermocautery. The glass capillary 

 was held by the operator in a groove on a stand a few centimeters 

 from the platinum blade, which was fastened so as to be immov- 

 able. An assistant controlled the heating of the platinum blade. 

 As soon as it heated to a dull glow, the operator slid the capillary 

 on its groove until the tip touched the glowing metal when it 

 was instantly slid back. The sliding of the capillary in a sta- 

 tionary groove insures a tapering to a point in a straight line 

 with the long axis of the capillary. In his paper Chabry dis- 

 cusses this method in some detail, pointing out ways of avoiding 

 difficulties in the technique ('87, pp. 175-178). Chabry also 

 suggested the use of insect mouth parts, annelidan bristles and 

 the spicules of sponges for the tips of microdissection needles. 

 Barber suggested fine-pointed needle crystals, or the sharp, stiff 

 hairs taken from the body of a house fly. A pipette with a fairly 

 large opening is made and the hair or crystal is drawn partially 

 into it. The fine point projecting from the tip of the pipette is 

 then used as a probe or dissecting needle. Such needles could be 

 used only on very delicate soft objects. 



Needle points may also be made by grinding one end of a fine 



