PIROPLASMA CANIS 593 



Kaumanns, in a paper read before the 1909 (Chicago) Meeting 

 of the American Veterinary Association, and published in full in the 

 Proceedings of the Association, strongly advocates the crossing of 

 American cattle with Brahma cattle from India for the purpose of 

 producing a natural immunity. He states that only 35 per cent, 

 of Indian blood is required to produce a race almost entirely immune 

 against Piroplasma bigeminum infection. The great difficulty in 

 carrying out such a plan consists in getting Indian cattle free from 

 latent trypanosoma infection. In attempts made in the past it was 

 found that a high perentage of such cattle, though examined thor- 

 oughly before exportation from India, were found infected with surra 

 upon arrival in the United States. Evidently the journey and the 

 change of climate awakened the latent trypanosomiasis. 



PIROPLASMA CANIS. 



The piroplasma infection in dogs was first described by Piana and 

 Galli-Valerio in Italy, in 1895. The two investigators recognized 

 the similarity between the parasites in the dog's blood corpuscles 

 and those in Texas fever, and called them Piroplasma bigeminum, 

 var. canis. They were subsequently found in dogs by a number of 

 authors and their morphology has been studied particularly by 

 Schilling, Nuttal and Graham, Kinoshita, Bowhill, LeDuc, Chris- 

 topher, and others. In several respects they are the best-known 

 representatives of the family piroplasma or babesia. 



In the fresh blood of the dog the intracorpuscular parasite can 

 best be seen at the height of the fever; it appears in the inside of 

 the erythrocyte as a light, highly refractive, sharply defined body, 

 generally found in somewhat enlarged red blood corpuscles. If 

 examined in fresh blood on a warm stage the protoplasm of the 

 parasite shows some contractility and appears to send out fine pro- 

 cesses. The latter may be so fine that they look like flagella. The 

 largest forms of the parasites are found in freshly infected dogs, the 

 smallest in old chronic cases. Blood smears stained with Roman- 

 owski's, Wright's, or Giemsa's stain show a small amount of oval 

 or pear-shaped, round or ring-shaped protoplasm stained bluish 

 with a dot stained red. The latter is the nucleus of the parasite. 

 The nucleus is not always small, sometimes it is quite large, and 

 occupies a considerable portion of the cytoplasm of the piroplasm. 

 These forms, after the fever has reached its height, and when the 

 temperature is going down, are also found outside of red blood cor- 

 puscles in the blood plasma. The microorganism is also found in 

 the internal organs, particularly in the liver, the kidneys, and the 

 bone marrow. 



The nucleus of Piroplasma canis is of indefinite shape, composed 

 of chromatin granules varying in form; it is generally situated eccen- 

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