214 BACTERIOLOGY. 



The true moulds have been observed grow- 

 ing spontaneously upon the cornea, in the 

 passage of the outer ear, upon the mucous 

 membrane of the larynx and in the lungs ; in 

 these places they can also form spores. The 

 internal organs to which the germs must be 

 conveyed by means of the blood vessels are 

 rarely affected by moulds, since the moulds as 

 a rule grow only superficially. On the other 

 hand it is easy to cause infection of the in- 

 ternal organs of the lower animals with moulds 

 by injecting spores into their circulation ; but 

 new spore-formation never occurs under these 

 conditions. There is, so far as I know, only one 

 instance where an infection of man has taken 

 place by way of the intestine. In one species 

 of Mucor a form and arrangement of the my- 

 celial threads occurs which recalls very strik- 

 ingly the ray-fungus. It is a most remarkable 

 thing that these disease-producing moulds, 

 like Aspergillusfumigatus 2J&&flavescens, Mucor 

 rhizopodiformis and corymbifer, although not 

 usually able to act pathogenically, and gen- 

 erally unable to adapt themselves to a parasitic 

 existence, are yet sometimes able to enter im- 

 mediately upon the production of disease on 

 the sole capital of characters acquired through 

 a saprophytic habit of life. This striking ex- 

 ample shows that pathogenic bacteria must 



