VI] 



METHODS OF PREPARATION 



47 



in the Oak, in Fig. 30, but which may be inferred from 

 comparison of dissections and sections of numerous species. 



F 



Fig. 30. Oak, Quercus Robur. A flowering shoot, with male catkins <? 

 and female clusters ? . B plan-diagram of the bud, showing the nu- 

 merous stipular bud-scales in five ranks outside, and the spiral leaves, 

 each with a pair of stipules, inside. The numbers indicate the sequence 

 in the spiral, and are placed in the position of the leaf which would belong 

 to each pair of stipules. F subtending leaf (Ei). 



Since there is room for much more investigation along 

 these lines, it may be interesting to refer to the laboratory 

 methods adapted to the preparation of serial sections of 

 buds. 



The bud is first hardened in any suitable fluid such as 

 absolute alcohol, chrom-acetic acid, or Flemming's fluid, 

 so that the delicate leaves and axis inside may be made 

 sufficiently tough to resist tearing as the razor passes 

 suddenly from the scales to the interior : about a day is 

 necessary for this. In some cases it may be necessary 

 to remove the hard outer scales in order that the fluids 

 may penetrate. It is then thoroughly washed to remove 

 the chromic acid or Flemming's fluid, if such are em- 

 ployed, and placed successively in alcohols of 50 / > 70 / , 



