160 



PLANT PARASITES. 



FIG. 85. ASPERGILLUS GLAUCUS. 



Showing mycelium, from which arise the spore- 

 bearing structures, the sporangia borne upon the by- 

 phae. 



furfur, Trickophyton tonsuraiis. There is a close morphological resem- 

 blance between these forms. 



Achorion Schonleinii, the favus fungus, is formed of a much -branching 

 mycelium from which the spores are directly developed (Fig. 86). It 

 grows readily on artificial cul- 

 ture media, such as nutrient agar 

 and gelatin, at the temperature 

 of the body. This fungus is most 

 apt to grow upon the hairy part 

 of the head, where it forms small 

 surface crusts and grows into the 

 shafts and root sheaths of the 

 hair, exciting inflammation in the 

 adjacent tissue. Trichophyton ton- 

 surans develops in the form of a 

 moderately branching mycelium, 

 forming comparatively few spores. 

 It grows in the skin, either about 

 or apart from the hairs, or in the 

 nails, inducing the lesions of vari- 

 ous phases of herpes, w r hich differ 

 considerably, depending upon the 

 particular structures involved. 

 At body temperature it grows readily on artificial culture media, differ- 

 ing markedly in appearance from Achoriou. 



Microspor on furfur, the mould fungus causing pityriasis versicolor, is 

 more prone than the Achorion to the development of many spores, but 

 otherwise considerably resembles it morphologically. It has not yet been 

 cultivated on artificial media. By its infiltration of the epidermis, espe- 

 cially of the body and upper extremities, 

 it causes larger and smaller yellowish or 

 brownish patches. 



The more complex types of moulds are 

 only occasional dwellers in the human 

 body and appear to be but rarely the 

 cause of disease, passing, rather, a sapro- 

 phytic existence on dead material in parts 

 of the body which are in communication 

 with the air. Thus they may be found 

 growing on accumulations in the external 

 auditory canal, in dead tissue in the 

 lungs, on walls of cavities, dilated bron- 

 chi, etc. Many cases have been reported, 

 however, in which the moulds, especially 



aspergillus, have been the apparent excitants of serious lesions in men 

 and animals. 



A lowly form of micro-organism frequently found growing in the 



PIG. 86.-ACHORION SCHdNLEINII FAVCS. 



From a culture. 



