290 BACTERIOLOGY FOR NURSES 



Theobald Smith described them more fully and established their 

 relationship to the disease of cattle known by various names, such 

 as Texas fever, tick fever, hemoglobinuria, and red-water fever. 

 The disease is characterized especially by destruction of the red 

 blood corpuscles and infection of the spleen and liver. So far as is 

 known ticks are solely responsible for its spread. After fertilization 

 the female gorges herself with blood, then drops to the ground 

 and there lays about 2000 eggs, depositing within the shell of each 

 sufficient blood to serve the embryo as food. The insect dies 

 within a few days after the egg laying has been completed. The 

 eggs hatch in about three weeks, and the larvae, containing within 

 their bodies some of the blood of their mother, crawl about until 

 they die or have the opportunity of attaching themselves to another 

 animal. If the larvae are the progeny of an infected mother they 

 thus become the means of further disseminating the disease. 



Similar infections affecting other animals have been shown to 

 be due to Babesia-like parasites. 



Plasmodia. For many centuries malaria has appeared in 

 certain regions as a veritable scourge, yet nothing definite was 

 discovered as to its cause until the latter part of the nineteenth 

 century. The fact that it remained prevalent in certain areas 

 and not in others led to the supposition that atmospheric condi- 

 tions were in some way responsible and to its being termed " ma- 

 laria " or " bad air." 



With the establishment of the theory that each infectious 

 disease is caused by a specific infecting organism the study of 

 malaria was taken up with enthusiasm. Several investigators 

 described bacterial forms which they thought might be the causal 

 agents, but their findings were disproved. In 1880 Laveran, 

 a French military surgeon stationed in Algiers, announced that 

 he had discovered a parasite in the blood of malarial patients 

 which was found to be a protozoon of the class Sporozoa. His 

 discovery was confirmed by the independent researches of two 

 Italian investigators, Marchiafava and Celli, who gave the organ- 

 ism the name of Plasmodiwn malarias. The term Hemameba has 

 been suggested as more appropriate and is frequently employed, 



