12 PRACTICAL HISTOLOGY [ll 



d. Choosing a corpuscle, either elongated or having 

 several processes, watch carefully its amoeboid move- 

 ments; make half-a-dozen drawings of its outline at 

 intervals of about twenty seconds. As a rule the 

 coarsely granular corpuscles put out few and rounded 

 processes, and the finely granular corpuscles put out 

 more numerous and more pointed processes. 



e. If it is desired to watch the movements for an hour or so 

 the drop should be protected from evaporation, (a) Melt a little 

 glycerine jelly (cp. App. p. 314) on a warm bath, keep the 

 cover-slip in place by gently holding a lifter against one edge, and 

 with a small brush, brush a little glycerine jelly over the edges 

 all round. ()3) If the slide is to be warmed, use melted paraffin 

 (of low melting point) instead of glycerine jelly. Before applying 

 the paraffin, dry the slide at the edges of the cover-slip with 

 blotting-paper, and warm the slide. Olive oil may be used 

 instead of glycerine jelly or paraffin. 



3. a. Hanging drop. Cut out a number of pieces 

 of blotting-paper about 3 cm. by 2 cm. Place them 

 together so as to make a pad. With scissors or cork 

 borer cut out from the centre of the pad a hole a little 

 smaller than the qover-slip to be used. Dip the pad 

 in salt solution 0*6 p.c. and place it on the slide. On 

 the centre of a cover-slip place a small drop of lymph, 

 and lower the cover-slip over the hole in the pad, so 

 that its edges touch the blotting-paper all round, and 

 the drop hangs in the centre and does not run off to 

 the pad. Thus a small moist chamber is formed. The 

 pad should be kept wet by adding a little water to one 

 edge from time to time. Examine the movements of 

 the white corpuscles under the microscope. 



b. Lymph crowded with white corpuscles, many in active 

 movement, may be obtained in the following way. The brain of 



