

Lesson III. 

 BLOOD (Concluded). 



(a) Fibrin. 



Place a larr/e drop of blood nn the slide, allow it to clot par- 

 tially; cover with a cover slip. Wash gently with a currentof water 

 until nearly all the red V)]()od cells have been washed out. Run a 

 few drops of a 1% solution of methylene blue under the cover 

 glass. 



Examine with high power. Sjuall glistening fibrillse 

 woven into a network will be seen ; these are fibrin filaments. 

 The nuclei of the white blood cells will be stained l)lue. 



(b) Teichmann's Crystals, Haemin Crystals, Chlo- 



ride of Haematin. 



Several weeks ago the. blood of a maniinnl was allowed to flow 

 on a piece of clntli. Cut out a small piece of tlie cloth with a por- 

 tion of the blond-stain on it. Tease it on a slide in a few drojis of 

 normal salt, and set it aside until some of the stain soaks out into 

 the solution. In case the normal salt begins to evaporate add now 

 and then a drop of the solution in order to keep the teased fibres 

 well soaked. Wlien some of the ijlood has been dissolved by the 

 salt solution, remove tlie cloth (il)res, and set tlie slide away to evap- 

 orate. If care be taken not to (/rt tJie slide too hot, the evaporation 

 can be hastene<l bj- holding the slide over a gas flame. When the 

 evaporation has been completed, scrape what is left on the slide int_i_ x 

 a small mass, and add one or two drops of glacial a(;etic acid, cover 

 with a cover glass, and heat over a fiame until bub})les form. Con- 

 tinue the heating till the a(ud has evaporated. Run a drop of water 

 under the cover glass, and examine for Teiclimann's crystals. If 

 present, the cover glass may be removed, dried, and mounted on 

 balsam. 



Study under high power. The crystals are seen in the 

 form of rhombic plates or rhombic rods of a brownish-red 

 color. 



(c) Teichmann's Cyrstals from Pigeon's Blood. 



Prepare as (b) of this lesson. 



