264 THE PROTOZOA 



producing the disease. The infection can also be conveyed to healthy 

 districts by the artificial dissemination of mature forms of the ticks, 

 which does not take place when the ticks are removed from the infected 

 cattle before they are driven on new tracts of land. The Pyrosoma 

 bigeminum, in certain respects, is somewhat similar to the malaria 

 organism, but is distinguished by dividing into two, and producing no 

 pigment. Although many particulars in their development are not suffi- 

 ciently cleared up, their place with the amoeba is certain. 



Immunity. Koch recently stated in his address to the Colonial 

 Society, Berlin, that he was able to infect healthy cattle with ticks 

 taken from diseased ones, and had succeeded in conferring immunity 

 against Texas fever as follows : Healthy animals were inoculated 

 with the blood of the animals infected by young ticks, and Texas 

 fever produced, and the process continued for several generations, 

 until the disease was produced in a number of animals which re- 

 covered. These recovered animals were infected a second time with 

 the blood of sick animals, being immune to the mild form of the 

 disease produced under the conditions of the experiment. The 

 immune animals were next taken to the coast and turned out with 

 an affected herd, but did not become affected. They were finally 

 inoculated with the blood of an animal affected with a severe form 

 of the disease, when only one of the immunized animals became 

 affected. 



BABESIA BOVIS (STARCOVICI). 



This parasite was first found by Babes in the red blood-corpuscles 

 of the blood of cattle affected with hsemoglobinuria in Roumania. 



Microscopical Appearances. It is found throughout the vascular 

 system, either as round or lanceolate-shaped bodies, mostly lying in pairs 

 or undergoing a process of division, and staining like bacteria. In the 

 fresh state they are non-motile, and measure about 1 />t, and in stained 

 specimens about 0'6 /x in diameter. In the commencement of the 

 attack large pear-shaped, irregular, staining bodies were also observed. 



The symptoms of the disease in the affected cattle are similar to 

 those of Southern fever. 



Haematuria is frequent during the life of the animal, the attack 

 lasting about five days. 



The chronic stage sometimes occurring in Texas fever was not 

 observed. According to Babes, the ticks play an important part in the 

 production of the Roumanian disease, the blood parasites increasing in 

 the bodies of the ticks. 



