788 BISECTIONS FOE LABOKATOKY WOKK 



(B) THE WHITE BLOOD CELLS (Leucocytes; Amelocytes). 



(1) Mount a drop of blood in Toison's solution under cover-glass. 

 Note the several types of white blood cells: (a) small mononuclear; (b) 

 large mononuclear; (c) polymorphonuclear ; and (d) note also a group 

 of blood platelets (plaques). Are the latter elements capable of ameboid 

 motility? What is their derivation? Are they true cells? What is 

 their most probable function? 



(2) Study carefully with oil immersion lens a blood smear stained 

 with Wright's (or Basting's, Ehrlich's triacid, or Jenner's) stain. 

 Identify and sketch (172) the various types of leucocytes: (a) lympho- 

 cytes (large and small) ; (b) large mononuclear and 'transitional' non- 

 granular leucocytes; (c) polymorphonuclear neutrophil leucocyte; (d) 

 eosinophil leucocyte; (e) basophil leucocyte (mast cell); and (f) blood 

 platelets. Note relative size, shape of nuclei, granular cytoplasmic con- 

 tent, and relative abundance of each type. Make similar study of rab- 

 bit's blood. (Here the neutrophils are replaced by similar cells with 

 fine eosinophilic, 'special', granules. In amphibia and reptiles the neu- 

 trophils are replaced by eosinophils with ellipsoidal granules.) 



(3) Study the contents of a vein in a stained section. Note the vari- 

 ous shapes of the red corpuscles, and identify the white blood cells present. 



(4) Make mount in Toison's solution of frog's blood. Note the 

 ellipsoidal nucleated red corpuscles, the white blood cells (a, small, large 

 and 'transitional' non-granular leucocytes; b, polymorph neutrophils; 

 c, eosinophils; and d, basophils) and the small spindle-shaped throm- 

 bocytes. Sketch (173). Watch a large leucocyte in ameboid progres- 

 sion. Sketch several steps (174). 



(5) Make similar mount and study of bird's or turtle's blood. How 

 does it differ from frog's blood? How do sauropsid bloods differ from 

 mammalian? rabbit's blood from human blood? 



(C) FIBRIN. 



Place a small drop of blood on slide and spread out thin, allow 

 to coagulate slowly. Breathe on the coagulum at intervals through 

 a period of about a quarter of an hour. Add a drop of methylene 

 blue, and allow it to act for several minutes. Rinse in water; dry 

 thoroughly and mount under a cover-glass in balsam. Examine the 

 thinner portions of the coagulum for the fibrin net. Sketch (175). 

 Study and sketch (176) also a small area of the fibrin net from a 

 stained section of a blood clot. Difference between plasma and serum? 



