50 



PRACTICAL HISTOLOGY. 



pale corpuscles of the frog or newt may be investi- 

 gated with the same apparatus as was used for the 

 observation of mammalian blood at the temperature 

 of the body. But it will be found that if the tempe- 

 rature be allowed to rise so high as 38 0. the move- 

 ments of the corpuscles of these cold-blooded animals 

 will soon permanently cease, the corpuscles being 

 killed ; so that unless this result is desired, some fat 

 of lower melting-point must be employed to indicate 

 the temperature limit which is not to be exceeded. 



Preparation 18. Action of Electric Shocks. 

 For this a slide must be specially prepared by 

 cementing on to its upper surface with sbellac var- 



Glass slide, with two strips of tin-foil, one of which pusses round to the 

 under .surface, where it rests on the brass stage of the microscope ; 

 the other strip is isolated from the stage, and may be connected to 

 the outer coating of a Leyden jar, the charge of wh'ch is ma.de to 

 pass between the points by connecting the knob of the jar with the 

 brass-work of the microscope. Opposite a, a small piece of the foil 

 is fixed to the under surface of the slide, so that this end shall be 

 level with the other. 



