PARASITES AND DISEASE (VEGETABLE PARASITES) 181 



small tubercles to masses the size of an orange or 

 larger, occurring in bones, periosteum, muscle, skin, 

 brain, lungs, liver, kidneys, heart, testes, and adrenals. 

 These masses are composed largely of round cells from 

 the blood-vessels and various proliferated connective- 

 tissue cells of spindle shape or irregular forms. Epithe- 

 lioid cells are few in number. There are various changes 

 in the vessel walls and new formation of blood-vessels. 

 Necrosis may occur at the center of gummata, and fatty 

 or myxomatous degeneration is common. Atheroma 

 of the arteries may lead to softening of the brain. 



Morbid Physiology. It is probable that the physio- 

 logic disturbances in this disease are due to the germ 

 itself, which is recovered from all the lesions of the dis- 

 ease rather than from a specific toxin. Antibodies are 

 found in the blood of infected individuals, and this fact 

 is taken advantage of in the Wassermann or deviation 

 of complement test. All efforts to establish either 

 active or passive immunity have thus far failed, 

 though Ehrlich has succeeded in ridding the system of 

 the disease by injections of an arsenic preparation 

 termed salvarsan or "606. " 



RELAPSING FEVER 



Definition. A specific infectious disease, caused by 

 the Spirochaeta obermeieri, characterized by recurring 

 paroxysms of fever and separated afebrile periods. 



Etiology. Overcrowding, deficient food, squalor, and 



