Donovan bodies been found in the peripheral blood, and this only when the temperature was high, but they are to be seen sometimes in countless numbers in the juice obtained by hepatic or splenic puncture. Before puncture exclude a leuchæmia with its vast leucocytosis, otherwise a fatal hæmorrhage may occur.
Blackwater fever, whether due to malaria (or to a piroplasma?) almost always shows parasites in the red corpuscles at the outset, and has no leucocytosis; a pocket spectroscope is of use in recognising the hæmoglobin, and very often methæmoglobin bands in the urine, for sometimes a dark urine is said to contain blood or hæmoglobin when such is not the case. Yellow fever resembles it in some cases, but has a leucocytosis and no parasites in the blood.
Plague may begin with a rigor in exactly the same way as malaria, but it has a leucocytosis greater than in any condition ordinarily met with, ranging from 20,000 to 100,000. The Bacillus pestis can be cultured from the blood in about a third of the cases as found by the German Plague Commission. No practical value attaches to serum diagnosis in this disease.
Cholera also shows a high leucocytosis, varying between 14,000 and 600,000. Rodgers
