PART III.] Animals in which the Flagellated Organisms have been Found. 637 



mass in the preparation, but in this instance, as represented at the right half of Fig. 66, 

 the parasite had fixed itself at a point about 3 /x, from the end, and to swing itself, 

 as from a to 6, from this fixed position. It will be noted that the part of the body 

 by which the parasite attaches itself here corresponds with that represented as having 

 been attached to the red blood-corpuscle in a previous figure. In this instance, also, 

 the lash was observed to manifest incessant screw-like movements, the movement 

 apparently commencing at the tip of the flagellum and proceeding rapidly upwards 

 until the point of attachment to the granular mass was reached, and here it stopped 

 abruptly. 



Many attempts were made to demonstrate the presence of another flagellum at 

 the opposite end, but without any satisfactory result. In preparations made by drying 

 a film of the affected blood on a cover-glass both ends of the parasite are often seen 

 to be very pointed, but in all cases a distinct flagellum could only be made out at 



Fig. 66. — Different methods of attachment to foreign bodies observed 

 in two specimens of the organisms from the blood of a rat. The 

 arrow along the middle figure indicates the direction of progi'es- 

 sive movement, x 1000 diameters. 



Fig. 67. — Action of gentian- violet on 

 specimens of the organisms from 

 the blood of a rat. x 1000 dia- 

 meters. 



one end. When a solution of gentian-violet is added to such a slide the parasites are 

 rapidly stained and present a granular appearance throughout, granules being frequently 

 distinguishable as far as the extreme tip of the flagellum, as may be observed in Fig. 67. 

 Occasionally the flagellum appears to be retracted, as shown in the sketch in the middle 

 of the figure, and I have sometimes thought that such a retraction of the flagellum 

 could be observed whilst the organism was in a condition of extreme activity. The 

 specimens in this figure were carefully outlined to scale by means of the camera lucida. 

 I am wholly unable to suggest any explanation for the presence of these flagellated 

 parasites in the blood of animals. It will be recollected that they have now been 

 observed in the blood of the horse, camel, and hamster, in addition to that of the rat ; 

 and, further, that they have been found in the blood of two dogs, but whether as the 

 result of intentional inoculation or otherwise must for the present be left undecided. 

 As regards the season in which they may be detected, I find that there are entries 

 in my note-book of their having been seen, at one time or another, in the blood of 

 rats in nearly each month of the year. 



