CHAPTER 7 



Technics for Avian Blood 



Lack of satisfactory technics is one of the rea- 

 sons why studies of avian blood have not been 

 carried forward as energetically and successfully 

 as have studies of mammalian blood. Students 

 of avian hematology have found that they fre- 

 quently get unsatisfactory results when they at- 

 tempt to apply technics that are known to be suit- 

 able for studying the blood of mammalian species. 



Over a period of years this Laboratory has 

 modified a number of commonly used technics to 

 suit the needs of avian hematology. 



THE MICROSCOPE AND LIGHT 



Perhaps the greatest deterrents to accurate and 

 critical study are ( 1 ) lack of a good microscope, 

 (2) lack of a good light source, and (3) deficien- 

 cies in setting up and using microscope and light. 



Here is what one often finds in a laboratory: 

 The "good" microscope is tucked away in a box. 

 When a special occasion arises, it is brought 

 forth and placed on a table close to a 75- or 100- 

 watt bulb or a lamp with a frosted glass in front. 

 Then the condenser is dropped below the level of 

 the stage until the amount of light is right, or the 

 diaphragm is closed so that the object shows up 

 well. 



For a quick look with low magnification, such 

 procedure may be satisfactory, but efforts are 

 often made to do critical studies under an oil im- 

 mersion lens with this type of set-up. The efforts 

 are disappointing because the microscope is pre- 

 vented from giving top-quality perfomiance. 



Many good books have been written on the 

 use of the microscope. Nevertheless it is not 

 uncommon to see research workers, technicians, 

 veterinarians, and physicians using the instru- 

 ment as if there were no directions. Correct use 

 is emphasized here not only because the authors 

 hope that their comments may be helpful to other 

 workers, but also because it is desired to assure 

 the reader that the structures depicted in the il- 

 lustrations have actually been seen in specimens. 

 The reader who fails to locate, in specimens of 



his own, the small structural and tinctorial dif- 

 ferences depicted here should not conclude that 

 they do not exist; he should consider the possi- 

 bility that he is not working under optimum con- 

 ditions. 



The information that follows was obtained 

 from the late Dr. Max Poser of the home office 

 of Bausch & Lomb Optical Co. and from Mr. H. 

 L. Shippy of the Detroit office of that company. 

 Similar information has been presented by Dr. 

 Oscar W. Richards in Color and Illumination, 

 published by the Spencer Lens Co. Two other 

 useful reference items by Dr. Richards will be 

 found in Literature Cited (Richards, 1938 and 

 1949). Another reference (Spitta, 1920) has 

 provided particularly helpful explanations of the 

 differences between achromatic and apochro- 

 matic lenses, and of why Huyghenian eyepieces 

 should he used with the former and compensating 

 oculars with the latter. 



An ideal light source is a small, brilliant point 

 of light that is passed through a lens designed to 

 produce parallel or nearly parallel rays. All 

 the drawings in this Atlas were made with a tung- 

 sten arc light. 



The lamp should be placed about 2 feet in 

 front of the microscope and the image of the light 

 source brought to a focus on a white card placed 

 in front of the microscope mirror. Adjustments 

 in focus can be made by moving the lamp con- 

 denser in and out. Just in front of the con- 

 denser lens of the lamp is a leaf diaphragm, which 

 should l>e wide open at this stage of setting up 

 the lamp and microscope. The next step is to 

 place a clear blue daylight filter in one of the 

 three slots in front of the lamp diaphragm. The 

 slots are constructed to hold 2" x 2" filters. One 

 may purchase a good lamp capable of giving 

 critical or Kohler illumination,' then nullify its 

 value by placing a ground glass in the path of the 

 light. 



' The essential differences between critical and Kijhler il- 

 lumination are given by Richards ( 1954) in a booklet ac- 

 companying each research microscope when purchased. This 

 booklet also contains a helpful bibliography. 



222 



