G8 



Mr. E. H. Boss. 



[Jan. 23, 



for much information, seems to have been the first to suggest the possibility 

 of their parasitic nature, and he mooted an analogy to the Cytorryctes variolas 

 or vaccina}. Goldhorn (1905) boldly called them leucocytozoa. The most 

 recent work published on the subject is that of Schilling (1911). He has 

 examined these bodies by " vital " staining with Azur, and he has described 

 some of the earlier stages of their development while in the mononuclear 

 leucocytes (lymphocytes). He believes that the rod stage precedes the 

 granule stages, and this has caused him to adhere to the opinion that 

 Kurloff's bodies must be classed with the Chlamydozoa, symbiotic structures, 

 or vaccine inclusions. 



Early in 1911, while examining a guinea-pig's blood by a new jelly 

 method of examination of blood cells, H. C. Eoss saw Kurloff's bodies, and 

 pointed out to me that the method demonstrated the probability of their 

 parasitic nature. The new method, which was devised partly at the 

 suggestion of Sir Eonald Eoss, K.C.B., has already been fully described 

 (H. C. Eoss, 1909) ; the bodies then seen were in the earlier stages of their 

 development. But the inclusions stood out so clearly by this method that 

 I determined to continue the observations, for this technique seemed to 

 show details of structure which had not been described before ; and since 

 by the new process the bodies can be subjected to the action of various 

 stains and chemical agents there was a possibility of the phases of their 

 development being observed. I may state that I have now been able to 

 convince myself that these bodies are living parasites of the mononuclear 

 white corpuscles (lymphocytes), and henceforth in this paper I propose to 

 call them such. 



I use a modification of the original jelly method — it is as follows : — A 

 2-per-cent. solution of agar in water is boiled, sterilised and filtered. To 

 5 c.c. of the filtrate is added - 5 c.c. of a 10-per-cent. solution of sodium 

 chloride in water, and 05 c.c. of a 1-per-cent. solution of Azur II in water. 

 The total bulk of the mixture is made up to 10 c.c. in a test-tube. When 

 molten, a small quantity of the jelly is allowed to spread itself in a thin 

 film on a microscope slide and to cool and set. Then a drop of guinea-pig's 

 blood (or titrated blood) containing Kurloff's bodies (about 90 per cent, 

 of the guinea-pigs examined by me, and which were obtained from dealers 

 in England, are infected) is placed upon a cover-glass, and this is inverted 

 on to the set jelly. The blood spreads out between the cover-glass and the 

 surface of the jelly, and, after an interval of five minutes, during which 

 the blood corpuscles come to rest, the specimen may be examined under 

 the higher powers of the microscope. After a further interval of a few 

 minutes — the exact period varying slightly with the temperature of the 



