Chapter XIV: Blood 101 



meter of undiluted blood contains 100 times as many, or 400,000 times 

 the number in one square. What result do you obtain ? 



"After finishing the count, clean the pipette by successively drawing 

 into and expelling from it water, alcohol, and finally ether. Do not blow 

 through it, but cause the ether to evaporate by sucking air through the 

 tube. For counting the white corpuscles use the large pipette and dilute 

 the blood 10 times with one-third of 1 per cent, glacial acetic acid. The 

 acid destroys the red corpuscles and thus the white corpuscles are more 

 readily seen. Proceed in the same manner as for red corpuscles." (From 

 Laboratory Outlines for Physiology, by Guyer and Pauli.) 



IV. OBSERVATION OF THE BLOOD CURRENT 



a) Circulation in the web of a frog's foot. Wind a long strip of 

 cheese cloth around a frog stretched out upon a narrow piece of thin board, 

 leaving one hind foot exposed. Soak the cloth in water in order to keep 

 the animal's skin moist. Pin the extended foot onto a ring of cork in 

 such a way that the web between the toes is stretched over the opening 

 in the cork. Examine under the microscope. If the preparation is favor- 

 able leucocytes may perhaps be seen penetrating the walls of the vessel 

 (diapedesis) and passing into the surrounding tissues. 



6) Circulation in the mesentery. Inflammation. Immobilize a frog 

 (the male is better) by injecting a few drops of a 1 per cent, solution of cur- 

 are into one of the dorsal lymph sacs. Curare paralyses the nerve endings. 

 After waiting 20 minutes for the curare to be absorbed into the circula- 

 tion, cut open the abdominal wall for a short distance along the left side 

 and draw out several loops of the intestine. Pin out a favorable area of 

 mesentery over a cork ring, and, after covering it with a cover-glass, 

 examine under the microscope. Keep the parts moistened with normal 

 salt solution. Such a preparation is especially favorable for studying 

 the migrations of leucocytes through the walls of the vessels. Do not 

 have the mesentery stretched too tightly or the circulation will cease. 

 After a time the phenomena of inflammation may readily be observed. 

 It is hastened if some irritant (e. g., a drop of creosote) is applied to the 

 mesentery. 



MEMORANDA 



1 , For Demonstration of the Different Granules of Leucocytes, etc., see 

 Appendix C, I, under the general topic of blood. 



2. To Study Blood in Sections, ligate a small vessel in two places to 

 keep in the corpuscles, then remove the piece so prepared and fix it in 

 Gilson's fluid (reagent 15, Appendix B) or Hermann's fluid (reagent 26, 

 Appendix B). Imbed in paraffin and cut thin sections. Stain material 

 fixed in Gilson or other corrosive sublimate reagents by the hematoxylin 



