108 MASTITIS OF THE COW 



considerably. They are usually small and by magnifying 

 250 diameters are just barely visible. In less frequent cases 

 they are quite large and may be seen by magnifying 100 

 diameters. 



The fungus is very difficult to stain, is Gram positive, 

 but must be carefully decolorized. The filaments are not 

 infrequently acid-fast. 



Cultivation. — The fungus is exceptionally difficult 

 to cultivate. I have attempted its cultivation repeatedly 

 without success and therefore advise reference to text-books 

 on bacteriology for its cultural characteristics. 



Pathogenicity. — Since I did not cultivate the organ- 

 ism I performed no animal experiments. 



The actinomyces fungus is a cell parasite like the pyog- 

 enes and tubercle bacilli and one may therefore reach the 

 same conclusions in experiments with the actinomyces 

 fungus as with the pyogenes bacillus. One may also ex- 

 pect that the fungus injected into the udder will soon be 

 taken up by the leucocytes and removed from the milk. 

 These leucocytes carry fungus into the udder stroma, where 

 fungus colonies are formed which may destroy the milk- 

 ducts and finally be discharged into the milk after from 

 one to several weeks. 



Udder-infection 



This is rare. The actinomyces fungus always produces 

 a typical stroma-infection [interstitial mastitis]. 



stroma-infection [Interstitial Mastitis'] 



Like tuberculosis, this infection possesses a typical 

 chronic progressive character. 



Ports of Infection. — The organism can gain en- 

 trance through the teat canal, through wounds or through 



