THE BLOOD AND THE BLOOD-FORMING ORGANS. 381 



cells, but may be of practically the same size. Another type possesses 

 the same characteristics except that the granulations are of the eosinophile 

 or basophile variety. Finally, there are found under the same conditions 

 as the myelocytes large mononuclear cells without granulations, the so- 

 called "irritation forms." The nucleus stains deep blue with the triacid 

 stain, and the cell body a dark brown. Moderate degrees of mixed 

 leucocytosis are seen in the severe primary and secondary anaemias, dur- 

 ing the course and at the end of severe infections, especially in children, 

 but the most marked example is in the blood of spleno-myelogenous 

 leukaemia. 



Charcot-Leyden crystals are occasionally found, chiefly after death, in 

 the blood in leukaemia, usually at the same time with an increased num- 

 ber of eosinophile cells. 



Degenerative Changes in the Blood are usually indicated in the leuco- 

 cytes by variations in the percentage of normal and abnormal varieties, 

 rather than by alterations in the individual cells, for degenerating leuco- 

 cytes are usually quickly removed from the circulation. Staining re- 

 actions of the various granules, by which degenerative changes may be 

 recognized, have not yet been devised. In leukaemia, pernicious anae- 

 mia, and diphtheria, a diminished reaction to nuclear dyes has been 

 observed. In leukaemia, and in the severe infectious diseases, the leuco- 

 cytes may be extremely cohesive, and it is believed that a large quantity 

 of bacteria or toxins in the circulation may even effect a complete solu- 

 tion and destruction of leucocytes (leucocytolysis). Fatty degeneration 

 of leucocytes has been demonstrated. 



Melanaemia. In^.thig^condition the blood contains ; Ijij^r jmd_smjdle_r_ 

 irregular-shaped parlicles or masses of brown or black pigment. This 

 condition is most frequently theTlresult of intermittent and remittent 

 fever, particularly the severer forms. It may be accompanied by anae- 

 mia and leucocytosis. It does not occur in all cases of the above-named 

 affections. It may be transient in character. The pigment may be free, 

 or more usually is enclosed in leucocytes. Under the same conditions 

 pigment may be deposited in the liver, spleen, lyjnjjhjjiQdes, bone mar- 

 row, and bloodvessels. Owing tcTthe deposit of pigment in the organs 

 they may assume a gray or slate_ color? The pjgment developed in 

 malaria originates in the decomposition of the haemoglobin under the 

 influence of the plasmodium. Pigment which has been taken into the 

 lungs from the jiir, such as cojl dusL. etc. . majiJind its way into the 

 blood either before or after deposition in the bronchial or other lymph- 

 nodes, and may be afterward deposited in the spleen and liver. 1 



1 For further details concerning changes in the blood, consult Simon, " Clinical Diag- 

 nosis," 4th ed. Eicing, "Clinical Pathology of the Blood," 1908. Cabot, "Clinical 

 Examination of the Blood," 1904, or Wood, "Chemical and Microscopical Diagnosis," 

 1904. 



