Minnesota Plant Diseases. 75 



Cases of lumpy jaw in man, though not very frequent, are 

 well known. The disease is similar in all respects to that pro- 

 duced in cattle. The fungus is similar and the results are usu- 

 ally fatal. Infection takes place in all probability from cuts 

 by splinters or wounds by grass blades, or when a grass blade 

 is drawn through the mouth or grains in the field are sampled 

 by biting. The fungus thus appears to lurk in places similar 

 to those of the fungus of lumpy jaw of cattle. 



Green mold fungi also cause disease in man. Some dis- 

 eases of the outer and middle ear canal are of this nature. 

 Here the fungus grows as a saprophyte in the ear secretions 

 and by its presence sets up irritation and consequent inflamma- 

 tion. It is doubtful if the fungus in this case is a true 

 parasite. These molds, moreover, when inhaled into the 

 lungs in sufficiently large quantities, may produce lung and 

 bronchial troubles. The latter are often asthma-like in their 

 symptoms. Children are subject to the attack of one of the 

 yeast-like fungi, similar to the comb-scab of chickens and the 

 throat troubles of cats and dogs. As with the last two the in- 

 ternal throat-parts are attacked and scabs and pustules pro- 

 duced in which the fungus is found, giving rise to sore throats. 

 Somewhat similar throat troubles have been produced also in 

 adults by a similar fungus. 



Contrast of parasitism in plants and animals. A great dif- 

 ference is noticeable between the known number of fungi para- 

 sitic on animals and plants. The former have been estimated 

 as less than two hundred while the latter must now exceed ten 

 or fifteen thousand. This difference can, in part, be accounted 

 for by certain general differences in surroundings. Fungi as a 

 rule require neutral or acid media, while animal tissues are 

 usually alkaline. Plants offer in their tissues more air space 

 and thus furnish more air, which is essential to the growth of 

 fungi. The body temperature is, in all higher animals, above 

 that at which most fungi develop under normal conditions, and 

 finally, the resistance of the white corpuscles of the blood is an 

 important factor. Fungus parasitism on animals is, with per- 

 haps the exception of lumpy jaw, an immediately destructive 

 one, and shows no effect of mutual partnership between fungus 

 and animal parts. 



