THE MICROVIVISECTION METHOD. 



forceps and, when the glass begins to soften, lift it slowly from the 

 flame and pull with the forceps slightly more than at first, but 

 not too strongly. The hands should remain on the table during 

 the process and the pulling and lifting done by turning them 

 slightly outward. The capillary will separate with a slight tug 

 a feeling much like that experienced when a taut thread, held in 

 the fingers, is parted in a small flame. If the point is properly 

 made, it will appear as shown in Fig. 6, b, c and d. This capillary 

 has sufficient rigidity and it comes to a very fine point. The 

 tip is closed, but the lumen extends almost to the end. It is 

 evident that everything depends upon the amount of heat used 

 and the timing of the pull, and that these must vary slightly 

 with the height of the flame and the diameter of the capillary. 

 With a little experience, one can usually tell when a proper point 

 is made by the peculiar feeling described above. If too little 

 heat is used and the pull made too suddenly, the capillary may 

 part with a snap and the tip be found broken off short often 

 forming a serviceable pipette. If too much heat is used, the 

 capillary is apt to be drawn into a long hair (Fig. 6, e). 



4. After a suitable point is made, the end of the capillary is 

 turned up at right angles (Fig. 6, /). This is done by holding 

 the point of the capillary just back of the point above the small 

 flame and pushing up the end with the tip of the forceps or with 

 a needle. Not more than 5 mm. should be turned if it is to be 

 used in a chamber not over 8 mm. in height. If a good point is 

 made, e. g., Fig. 6, b, it is not necessary to turn the end at exactly 

 right angles. A pipette is made by jamming the tip of a needle 

 against the cover glass in the moist chamber to break off the 

 point. 



The forceps used in the making of the needles should be of a 

 size that can be firmly grasped in the hand. The fine tips should 

 be accurately set and almost parallel one another for a few milli- 

 meters. In order to give the tips a good, grasping, resilient sur- 

 face I dip them, before using, in a small vial of Sandarac varnish 

 which may be obtained from a dentists' supply dealer. As the 

 varnish burns if brought too close to the flame, it is well to use a 

 second forceps or a needle for bending the glass capillary. 



Fine points are not readily made from capillaries of a diameter 



