46 



PRACTICAL HISTOLOGY. 



which frog's blood has been collected and has coagu- 

 lated. A high power is to be employed, and the 

 capillary tube must therefore be very line indeed ; 

 and in order that the wall of the tube should be as 

 thin as possible, it must be drawn out from a piece 

 of glass tubing half an inch or more in diameter. 

 The capillary tube is filled with frog's blood, except 

 near the ends ; these are then sealed by holding them 

 successively in the flame for a second or two ; the 

 tube is then placed in a drop of glycerine on a slide, 

 covered with a thin glass, and at once examined. 

 The object of the glycerine is to correct in some 

 measure by its high refracting power the effect 



Fig. 12. 



White corpuscles of frog's blood migrated from clot. Highly mngnified. 

 The clot has shrunk considerably from the sides of the capillary tuba. 



upon the light of the cylindrical glass tube. After 

 a few minutes the clot is seen to be getting smaller, 

 and a layer of clear serum collects between it and 

 the glass; the quantity of this gradually increases, 



