PI RO PLASM A CAN IS 



495 



near the pointed extremity, from which a tail of loose chromatin runs along- 

 side the vacuole towards the blunt extremity. 



The corpuscle now ruptures and liberates the two parasites and some 

 granules, representing residual matter, from the parasite or the corpuscle, 

 or both. 



Two slight variations of the process have been described by Nuttall and 

 Graham-Smith; in one the two nuclei and their strands form an hourglass- 

 shaped mass, and in the other the strand and secona nucleus form a reticular 

 mass; but both develop into the stage depicted in the diagram. Four 

 pyriform parasites may be found in a corpuscle instead of two, and this may 

 come about by an invasion of the corpuscle by two pyriform shapes, which 

 proceed to division, or by the division of the uninuclear shape into two, 

 both of which proceed to develop regularly. Reproduction by gemmation 

 with the formation of one or two buds has been described by Breinl and 

 Hindle, and of many buds by Kinoshita. 



Flagellate Forms. — Nuttall and Graham-Smith in 1905 described large forms 

 in the blood of the first dog which they infected in Cambridge by ticks from 

 South Africa. These forms were found on the fourth, fifth, and tenth days, 

 and occurred in the peripheral blood and in that from a kidney. They 

 were sausage-shaped, with rounded or tapering extremities. In some the 

 chromatin was almost entirely concentrated in the middle, while in others it 

 appeared to be of loose texture. Kinoshita has seen similar parasites in 

 blood from the heart, the pancreas, and the lungs after death. The significance 

 of these parasites is not yet understood. 



Free parasites with flagella-like processes have been seen by Pound, Bowhill, 

 Le Doux, Nuttall and Graham-Smith, Kinoshita, Fiilleborn, and Breinl and 

 Hindle, the last-mentioned observers describing the development of large 

 biflagellate forms from the normal intracellular parasite. 



The significance of these forms is not understood, Breinl and Hindle 

 considering that they are such very transient stages in the life-history that 

 they may easily be overlooked. 



The development as given by Breinl and Hindle is associated with a 

 binucleated form. 



Cultivation. — Kleine, Nuttall, and Graham-Smith have attempted to culti- 

 vate Babesia cams in defibrinated blood. Kleine has observed elongated forms 

 with radiating processes, similar to those found by Koch in ticks. 



Nuttall and Graham-Smith have observed the same forms, but consider 

 them to be intracellular, the haemoglobin having nearly disappeared from 

 the red cells. 



Inoculation. — It was first shown by Dr. Corrington Purvis in 1900 that the 

 disease could be spread from dog to dog by blood inoculation. 



Infection from Ticli-Bites. — Piana and Galli Valerio, when they discovered 

 the parasite in 1895 Italy, suspected that it was transmitted by the tick 

 Ixodes reduvius L., but the first actual demonstration that this really took 

 place was by Loundsbury in 1901, by the bites of the tick Hcemophysalis 

 leacjii Audouin, in South Africa. 



Dermacentor reticulatus Fabr. is suspected as the spreader of the disease in 

 France. 



This subject has been carefully investigated by Loundsbury, who finds 

 that the parent tick, having gorged with blood, falls to the ground and lays 

 her eggs, which develop into six-legged larvae. 



These larvae do not infect the dog, which they attack as soon as possible, 

 and on whom they remain two days sucking blood. After dropping off, 

 they in due time shed their larval skin, and become eight-legged nymphs, 

 which again bite the dog, but do not infect it. 



The nymph, after dropping off, undergoes metamorphosis, and sheds its 

 nymphal skin and becomes the sexually mature tick, which is the only form 

 that spreads the infection, a fact confirmed by Nuttall. 



Christophers has traced out the development in Eurhipioephalus sanguineus 

 Latreille, thus finally confirming the idea of the transmission through the 

 tick. 



