III.] 



CRYSTALS FROM BLOOD. 



121 



cent, salt solution. Heat the mixture until it becomes brownish in 

 tint, add glacial acetic acid and heat. On cooling, crystals of hsemin 

 are obtained. Should there be any cubes of common salt present 

 irrigate with water, which soon removes the latter. Hsemin crystals 

 are insoluble in water. 



(a.) Observe the small brownish or black rhombic crystals, cither 

 singly or in rosettes, scattered over the field or on the surface of 

 the larger masses of blood (fig. 81). 



o 



FIG. 81. Hncmin or Teichmann's 



Crystals. 



FIG. 82. Leuksemic Blood. 



(6.) To preserve them, remove the acid, raise the cover-glass, 

 dry the preparation, and mount them in balsam. 



12. Enumeration of the Blood Corpuscles. See the author's 

 Outline* of Practical Physiology, Lesson VI., p. 42. 



13. Leukaemic Blood (H). If a small quantity can be obtained 

 from a patient in the hospital, examine it. 



(a.) Observe the great excess of colourless corpuscles. Accord- 

 ing to the variety of the leukaemia, they may be larger or smaller 

 in size than most of the coloured corpuscles (fig. 82). 



ADDITIONAL EXERCISES. 



14. Human Blood and Aniline Dyes (Hj. Make a cover-glass preparation 

 of human blood (Lesson II. 24). Ehrlich heated the cover-glass in an air- 

 oven to a temperature of 120 for several hours to coagulate the proteids. To 

 avoid this, place the covers for two hours in the alcohol and ether mixture 

 (Lesson II. 26), and then stain them in methylene-blue as directed for frog's 

 blood-corpuscles, or stain in I per cent. Spiller's purple or a weak alcoholic 

 solution of rosein. After washing and drying, mount them in xylol balsam. 



In the methylene-blue preparation the coloured corpuscles are unstained, 

 but some of the colourless ones have their nuclei stained blue, while the 

 surrounding protoplasm is unaffected ; in other colourless corpuscles the 

 granules in the protoplasm are stained. These corpuscles correspond to 

 Ehrljcli's basophile corpuscles. In the other preparations both the coloured 

 and colourless corpuscles are stained. 

 12 



