BY K. GKKIG SMITH. 587 



occur ill twos, sometimes even in fives and sixes. Wiien double, 

 the narrow ends are together, and it is undoubtedly only a matter 

 of technique to show that they are united by a connecting thread. 

 The pear-shaped parasite stains unequally; the part occupying 

 the bulb of the pear stains feebly or not at all, and it is assumed 

 that this is a Aacuole; the middle portion generally takes the 

 stain deeply. This form is not common in the corpuscle during 

 life, (i) for by the time that the parasite has grown to this shape 

 the corpuscle has become disintegrated and the organism free. It 

 is to 1^6 found in numbers soon after death, while if a section or 

 fihn be made immediately the animal dies, there is seen a mixture 

 of the younger with the presumably oldest form. In the 

 capillaries during the acute stage small double spindles are some- 

 times seen, each spindle being connected by a joining line. This 

 is probably an intermediate stage of the parasite. 



In fresh blood a small round spot is frequently seen close to the 

 periphery in some of the corpuscles: it is free from haemoglobin 

 and measures 0-5 /ix in diameter. It is also visible in stained pre- 

 parations, where it varies up to 0-6 fj., and is often divided. 

 Since this appears at the beginning of the attack and disappears 

 when the corpuscles begin to increase in number, it is not to be 

 considered as a degenerate form (i). It is contended by Celli and 

 Santori that this extremely small body is not the parasite, since 

 Marciafava had seen it in cases of malaria, and they themselves 

 had found it in healthy guinea-pigs as well as in rabbits and dogs 

 which had died of diseases other than tick fever. It is referred 

 to as a pseudoparasitic endoglobular body. It is possible that 

 the smallest form of the tick fever parasite may be of the same 

 diameter as the pseudoparasitic body; in this case they would be 

 morphologically identical. 



According to Celli and Santori, what is really the smallest and 

 probably the youngest type of the parasite measures from 1 to 

 1 -5 fi. It changes its shape as it moves about from place to place 

 in the corpuscle, becoming round, oblong, cylindrical, egg- or 

 pear-shaped in succession. It may occur singly, in pairs or threes 

 in one and the same corpuscle. It is strongly refractile and shows 



