Preface 



An atlas of hematology is a picture Itook that functions as a dictionary. 

 Minot, in his foreword to Atlas of the Blood in Children, hy Blackfan, Dia- 

 mond, and Leister (1944), aptly expressed the need for illustrations in 

 hematology when he stated, "Illustration is essential in hematology. The in- 

 adequacy of language to convey the appearance of disease to the mind renders 

 an appeal to the senses desirable whenever it can be employed, and when 

 the objects themselves cannot be presented the best substitute for them is to 

 be found in pictures." 



It is hoped that this Atlas will enable investigators to forge ahead 

 without the necessity for long delay in determining how the normal cell types 

 and developmental stages should appear. The identification of the early 

 and intermediate stages of development for most of the cell types has been 

 worked out for the first time. The results of this research have been inte- 

 grated with previous knowledge. All of the illustrations are original. 



With the population expanding at an ever-increasing rate, the demand 

 already is upon us to have available a stockpile of sound biological infor- 

 mation on many subjects in order quickly and accurately to solve future 

 problems of agriculture that will grow out of the necessity for making farm 

 production more efficient. The control of disease is an obvious method of 

 increasing our efficiency and is the objective of the long-range program 

 on normal avian hematology that was undertaken at this Laboratory. 



The subject matter covers not only tlie circulating blood of the adult 

 bird, ]jut also that of the embryo during its incubation from 2 days to 

 hatching, and it includes the developmental stages found in blood-forming 

 organs of both tlie adult and the embryo. The illustrations and text are 

 concerned not only with the appearance of typical blood cells but also with 

 the recognition of the atypical, the unusual, the abnormal, and the false. 

 It is believed that future investigators of lalood diseases of poultry will 

 rarely find a cell in their preparations that has not been illustrated here, 

 except cells invaded by organisms such as protozoan and other parasites. 



A biopsy that involves Jjlood is simpler and easier to procure than 

 is a biopsy of any other tissue of the body, and even from a drop of 

 blood nuich useful information concerning the health of the organism can 

 be obtained. 



It is intended that this publication shall serve the needs of the poultry- 

 man, the veterinarian, and the research worker in zoology, embryology, 

 endocrinology, physiology, virology, and nutrition when these persons are 

 confronted with the problem of identifying Ijlood cells in birds. It will 



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