19 
Babesia ovis or Piroplasma ovis is viewed as the cause of carceag, also known as ovine 
piroplasinosis. 
Piroplasma equi is viewed as the cause of equine piroplasmosis; and 
Piroplasma canis is accepted as the cause of canine piroplasinosis. 
All of these parasites are supposed (see p. 20) to be transmitted by 
ticks {Ixodoidea) and the symptomatology of the diseases is more or 
less uniform (see p. 39). 
Piroplasma donovani Laveran has been described as a parasite of man, causing non- 
malarial splenomegaly (Dum Dum fever; Kala-azar) in warm climates; but very 
serious doubts arise as to whether this organism is a Piroplasma, and a new genus 
{Leishmania) been proposed for it by Ross. 
The structures which Wilson and Chowning have found in “spotted 
fever” have been named — 
PIROPLASMA HOMINIS (Wilson and Chowning, 1903) Manson, 1903. 
1903. Pyroplasma hominis Wilson and Chowning in Anderson, 1903a, p. 506. — 
Wilson and Chowning, 1904a, p. 48. 
1903. Piroplasma hominis (Wilson and Chowning, 1903) Manson, 1903, p. 33. — 
Nuttall, 1904, p. 252. 
1904. Babesia hominis (Wilson and Chowning, 1903) Chauvelot, 1904, p. 93, in part. 
Wilson and Chowning (1902a, pp. 134-135) found structures in the 
blood of spotted-fever patients which they interpreted as protozoa, but 
they preferred “to make a fuller study of the life history of the 
organism before attempting to classify it more definitely than as a 
hernatozoon;” they call attention to its similarity to Piroplasma 
ligeininum and also to the parasite of malaria. For a complete 
description of this parasite the reader is referred to the articles by 
Wilson and Chowning (1902a, 1903a, 1904a), Cobb (1902), and Ander- 
son (1903a, 1903c). 
Neither Ashburn nor I, in a total of 400 hours of microscopic stud\^ 
of the fresh and the stained blood of typical cases, and in an exami- 
nation of a typical slide kindly sent to me by Wilson and Chowning, 
was able to find any Piroplasma; and Chowning was unable to demon- 
strate the organism to us in the fresh and the stained blood of a typical 
case. 
Inoculations . — Wilson and Chowning inoculated rabbits with blood 
of spotted fever patients, both in 1902 and 1903, and they found the 
parasites in the blood of the experiment animals. ln,1904 I inoculated 
rabbits with the blood of 3 fatal cases, as follows: 
Two rabbits inoculated with blood within thirty minutes after death of patient. 
One rabbit inoculated with blood taken from arm during life. 
Two rabbits inoculated with blood within two hours after death. 
The blood of these rabbits was repeatedly examined, but with nega- 
tive results. 
Since the observations of Wilson (in 1902, 1903), Chowning (in 1902 
and 1903, but not in 1904), Cobb (in L902), Wesbrook (in 1902), and 
Anderson (1903) all gave positive results, while observations (in 1904) 
