72 The Development of a Leucocytozoon of Guinea- Pigs. 



of these infected animals show, however, single or multiple white patches of 

 necrosis varying in size between that of a pin's head to that of a large pea, 

 and extending into the substance of the organ. But we have no proof, as 

 yet, of their direct relation to the parasite. 



Fixed specimens of the various stages of the development of this parasite 

 may be made by substituting an equal amount of a 1-per-eent. solution of 

 caustic soda in the jelly for the sodium chloride solution. By this means the 

 red blood corpuscles are laked, but the nuclei of the leucocytes and the 

 chromatin of the lynrphocytozoa stain well. The cover-glass can then be 

 lifted from the jelly and mounted while still wet in Canada balsam. Many 

 of the leucocytes with the contained parasites will adhere to the cover-glass 

 and will retain their stain. 



Since writing this paper, Hindle has published a preliminary note (Hindle, 

 1911), " On the Life-cycle of Spirochceta gallinarum." He asserts that 

 these spirochsetes possess an intracellular stage within the cells of the 

 Malpighian tubes of the tick, Argas persicus. In view of the life-history of 

 this lymphocytozoon of guinea-pigs his work is of great interest. 



I have to express my indebtedness to Dr. J. W. Cropper and to 

 Dr. H. Bayon for their help in these researches ; the latter was the first to 

 recognise the free swimming, spirochaete-like bodies. I also wish to thank 

 Prof. Minchin and Dr. Martin for much help and advice and the interest they 

 have taken in this work. 



Summary. 



Kurloffs bodies are parasites, lymphocytozoa inhabiting only the mono- 

 nuclear cells of the guinea-pig's blood. 



These lymphocytozoa have an intracorpuscular stage, and ultimately give 

 rise to free swimming, spirochsete-like bodies, which may be gametes. 



The development of the spirochsete-like body is demonstrated. 



The name Lymphocytozoon cobayce is suggested for this parasite. 



REFERENCES. 



1891. Kurloff, Ehriich's ' Die Anaemie.' 



1904. Burnett, ' Journ. Med. Research.' 



1905. Staubli, ' Deut. Archiv f. klin. Med.' 



1905. Goldhorn, 'New York Path. Soc. Proa' 



1906. Ledingham, 'Lancet,' London, June 16. 



1906. Ehrlich, quoted by Ledingham, ibid. 



1907. Howard, 'Journ. Med. Research.' 



1908. Pappenheim, ' Folia Hsematologica.' 



1908. Patella, ' Berliner klin. Woch.' 



1909. Hunter, ' Univ. Penn. Med. Bull. Phila.,' vol. 22. 

 1909. H. C. Ross, ' Roy. Soc. Proc.,' B, vol. 81, p. 97. 

 1911. Schilling, 'Centralb. f. Bakt.,' orig., vol. 58, Part 4. 

 1911. Hindle, 'Parasitology,' vol. 4, No. 4. 



