d2 veterinary I'ATilOLOGi. 



mother cell or it ma}' become detached and then pass through 

 a similar cycle. Under certain conditions the yeast plant may 

 develop into filamentous threads and in other instances may 

 produce spores. 



Saccharomyces was, for a considerable time, associated as 

 an etiologic factor in the production of carcinoma. It is prob- 

 able that the "carcinoma bodies" (dense refractile oval bodies) 

 are yeast cells but it is quite evident that they have no etio- 

 logic significance in carcinomata. 



Dermatitis in the human is, in some instances, of a saccharo- 

 mycetic origin and no doubt some of the resistant cases of der- 

 matitis in domestic animals have a similar cause. 



The principal pathogenic saccharomj-ces that concerns the 

 veterinarian is the Saccharomyces farciminosus, which has 

 been described by Rivolta as the Cryptococcus farciminosus. 

 This yeast is the cause of epizootic lymphangitis, a disease 

 which affects equines and primarily involves the cutaneous 

 Ivmphoid tissue. The disease is prevalent or has prevailed in 

 many localities in the United States, and in the Phillipines, 

 as well as, in India, Japan, China, South Africa, England and 

 Ireland. The principal lesions are located in the h^mphoid 

 tissue u'liich l)ecomes tumefied and inflamed and in which the 

 lymph sinuses are found to be engorged with coagulated Ivmph 

 and pus. The lymphoid tissue later undergoes central liquefving 

 necrosis and this is followed by the formation of pustules or 

 ulcers. After the discharge of the pus the ulcer gradually heals 

 and the related tissue becomes indurated. In a few cases 

 lesions have been observed in the liver and spleen. 



Two other pathogenic fungi tliat have not been satisfactorily 

 classified are the Actinomyces Bovis and the liotrvomyces 

 Ascoformans. These are the causative agent of Actinomvcosis 

 and Botryomycosis respectively. These micro-organisms as 

 well as the diseases they produce will be discussed later. 



Schizomycetes. (Bacteria). 



As will be noted by the foregoing scheme, bacteria are 

 classed among the lowest groups of plants. Each bacterium is 

 a single cell and contains no chlorophyll. 



The science of bacteriology is of recent development, because 

 early investigators were compelled to use comparatively crude 

 microscopes and because they were not familiar with the condi- 

 tions required for bacterial growth. The development of bacter- 

 iology was coincident with the discussion pro and con of the 

 theory of "spontaneous generation." This theory was disproved 



