BLOOD CELL VOLUME 



43 



BLOOD VESSELS 



tube. Make blank without plasma. 

 Compare in Evelyn or Klet-Summerson 

 colorimeter using filter to pass only light 

 of about 620 m^. Calculate as directed 

 for the colorimeter (Shohl, A. T. and 

 Hunter, T. H., J. Lab. & Clin. Med., 

 19-11, 26, 1829-1837). See also earlier 

 cell opacity method (Shohl, A. T., J. 

 Lab. & Clin. Med., 1939-40, 25, 1325- 

 1332). 



Blood Grouping technique does not properly 

 come in the scope of this book; but since 

 it is involved in fundamental medical 

 and biological problems the following 

 leading reference is given: Schiff, F., 

 and Boyd, W. C, Blood Grouping 

 Technic . New York : Interscience Pub- 

 lishers, Inc., 1942, 248 pp. 



Blood Protein. Coagulated blood protein 

 within the vascular lumina of stained 

 sections of fi.xed tissues is an artifact 

 in the sense that its appearance has been 

 greatly modified by the technique. It 

 is sometimes made up of particles of 

 quite uniform size and has been 

 mistaken for masses of microorganisms ; 

 but it does not exhibit both acidophilic 

 and basophilic staining reactions sug- 

 gestive of cytoplasmic and nuclear 

 components. 



Blood Smears. These should be made on 

 slides rather than on cover glasses for 

 several reasons. A larger film of blood 

 is thereby provided for examination. 

 Smears on slides are easier to make and 

 to handle . They can be studied without 

 covering them whereas a smear on a 

 cover glass cannot be moved about on 

 the stage of the microscope unless it is 

 mounted smear side down on a slide. 

 The colors are often more permanent in 

 smears on slides which are not covered 

 with cover glasses. A good way is to 

 spread a thin film of immersion oil over 

 them. This dries much more quickly 

 than balsam or any other medium under 

 a cover glass. 



Slides of good quality with ground 

 edges and scrupulously clean are neces- 

 sary (Cleaning Glassv/are). A finger 

 tip or ear lobule is first cleaned with 95% 

 alcohol. As soon as the surface has 

 dried a small puncture is made with a 

 previously sterilized needle. Special 

 needles with lance shaped cutting ends 

 are better than ordinary pointed ones. 

 A small droplet of blood should appear 

 on slight pressure. The first is wiped 

 away with sterile gauze and the second 

 and following ones are used. Unless 

 the blood is very strongly pressed out, 

 the differential count of white cells vyill 

 not be affected. Some advise holding 

 the fingers in hot water beforehand to 

 produce a temporary hyperemia in them 

 but this is seldom advisable. A droplet 

 of size sufficient to produce a smear of 



the desired thickness (determined by 

 trials ) should be touched to the surface of 

 a slide about 3 cm. from one end conven- 

 iently placed on a table. Immediately 

 the end of a second slide, with its edge 

 squarely across the first slide is brought 

 in contact with the blood on the remote 

 side of the drop from the nearest end of 

 the first slide. The blood spreads 

 quickly along this edge toward the sides 

 of the slide on the table which is steadied 

 with the left hand. The end edge of the 

 second slide is slowly but steadily 

 pushed the length of the first slide and 

 the blood is drawn out in a thin layer 

 after it. The angle of inclination of the 

 second to the first slide determines the 

 thickness of the smear. It is well to 

 make the first smear at an angle of about 

 45 degrees; increase it for a thicker 

 smear and decrease it for a thinner one. 

 In the making of smears it is important 

 to have plenty of elbow room. To make 

 good smears is a fine art and a credit to 

 the individual. 



Blood smears, whether simply dried 

 by waving in air or thereafter fixed by 

 gently heating, retain their staining 

 properties for a few days but they 

 should be colored without undue delay. 

 However they can be kept unstained or 

 stained if protected by dipping in 

 melted paraffin (Queen, F. B., Am. J. 

 Clin. Path., Techn. Suppl., 1943, 7, 50). 

 It is both wasteful and undesirable to 

 cover the whole slide with stain. Part 

 of the slide will have to be used for 

 record written with a diamond pencil. 

 Therefore draw two lines across the 

 slide near each end with a wax pencil or 

 a piece of paraffin. The stain added 

 with a dropper will cover only the inter- 

 vening part. For stains see Giemsa, 

 Wright, Ehrlich, Oxidase, Peroxidase 

 and Gordon's Silver Method. 



Blood Species Characteristics. References 

 to the literature on the blood of many 

 different kinds of animals and data on 

 their differential counts, total counts, 

 hemoglobin concentrations and so on 

 are often found of great service (Win- 

 trobe, M.M., Clinical Hematology. 

 Philadelphia: Lea & Febiger, 1942, 

 703 pp.). 



Blood Vessels. These comprise structures 

 of different sorts, existing in a wide 

 variety of environments, which can be 

 investigated from many angles. Con- 

 sequently to present examples of avail- 

 able techniques under the expected 

 headings involves a lot of mind -reading. 

 The blood vessels of the Skin are of 

 course the most accessible. Detailed 

 methods for their direct and indirect 

 study are presented by Sir Thomas 

 Lewis (The Blood Vessels of the Skin 



