72 



Miss H. L. M. Pixell. 



Pigeon 2. — Inoculated January 30. Intraperitoneum from peritoneal fluid 

 of Mouse D. February 26, peripheral blood tested, no parasites found. 

 March 19, appeared in perfectly normal health. 



I cannot account for this pigeon not becoming infected after being inoculated 

 with the peritoneal fluid of Mouse D, which contained numerous parasites. 



[June 19. — I understand from Dr. Mcolle that he has also found that 

 pigeons cannot be infected by inoculation of the virus after passing through 

 mice, though he has succeeded in infecting them easily directly from gondi.] 



Technique. 



Many smears were stained with Giemsa, and the presence of parasites was 

 easily tested in this way, although, as is well known, this stain cannot be relied 

 upon for cytological detail. On the whole iron hematoxylin was found to be 

 by far the best nuclear stain. Delafield's hannatoxylin also gave good results. 

 Twort's stain, borax carmine, paracarmine, Mayer's acid haemalum and 

 Mann's htematein were used with less success. Double staining was found to 

 be advisable in all cases. Orange G and eosin were quite satisfactory for 

 this purpose. No differential staining of the cytoplasm was effected by using 

 mixtures such as licht-griin and picric acid or picronigrosin ; both of these 

 were, however, useful for the stretched' omentum. Another useful mixture 

 for sections was eosin and licht-griin made according to Chatton's formula 

 (2, p. 254), which is a modification of Prenant's. The cytoplasm of the 

 parasite took up the eosin only, so apparently there are no reserve food- 

 particles or other green-staining inclusions. 



When fixed by osmic acid vapour and absolute alcohol for Giemsa staining, 

 the parasites, as usual, appear much larger (tigs. 7 and 8) than when fixed by 

 the wet methods generally employed. For the latter Maier's fluid gave very 

 good results — slightly better perhaps than Flemming's fluid or a mixture of 

 corrosive sublimate and acetic acid. 



Morphology of the Parasite. 



The living parasites are non-motile, but seem to be capable of slightly 

 altering their shapes. A specimen drawn with a camera lucida at intervals 

 of 5 or 10 minutes is shown in figs. 2, a-e. It appeared to be trying to free 

 itself from a mass of cellular debris. I would not like to say for certain, 

 however, that it was really changing its shape, for the apparent differences 

 in appearance may possibly have been due to slight invisible currents in 

 the medium causing the parasite to be viewed from different aspects. I 

 have also observed them apparently bending in the middle and turning over. 



