GENERAL METHODS. 



FIG. 6. Glass bot- 

 tle with glass rod 

 on the stopper. 

 After W. Behrens 

 (I). 



the slide, one may use with satisfaction the bottle shown in 

 Fig. 5, whose hollow stopper ends in a glass tube, while the 

 upper end is closed by a 

 rubber cap. By compress- 

 ing the rubber cap and then 

 allowing it to expand, fluid 

 is drawn into the stopper, 

 and may then be pressed 

 out in suitable quantities 

 by renewed pressure on 

 the rubber cap. With re- 

 agents which are to be used 

 only in drops, the bottle 

 figured in Fig. 6, whose 

 stopper is drawn out simply FIG. 5 Glass bottle 



. ,11 i with pipette. After 



into a glass rod, may be w. Behrens (i). 

 used. 



20. In order to prevent the collapse of delicate objects 

 when brought into clove-oil or xylol we may use the meth- 

 ods proposed by Overton (I, 12). 



I. If an object is to be brought into clove-oil or other ethe- 

 real oil, it is taken from the alcohol and placed in a small 

 disli containing a 10$ solution of the oil in alcohol. This 

 dish is then placed in a somewhat larger one or in a suitable 

 exsiccator, whose bottom is covered with solid calcium chlo- 

 ride. The alcohol is then gradually absorbed by the chlo- 

 ride, and the object becomes at last completely saturated 

 with oil. To prevent longer action of the alcohol, one may 

 transfer the objects from alcohol to water-free chloroform 

 and thence to a io# solution of clove-oil in chloroform, from 

 which, as in the last-described method, the chloroform may 

 be absorbed by calcium chloride. 



II. For transfer to xylol the objects are put in a dish with 

 a 10$ solution of xylol in alcohol and placed in a exsiccator 

 on whose bottom is pure xylol. Such an adjustment then 

 takes place between the two fluids by diffusion, that the 

 objects finally lie in nearly pure xylol. 



21. The transfer of very small objects from alcohol to 



