340 MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMIA. 



FIG. 123. 





123) in the stomach of an herbivorous beetle, tliePassulus cornutus, 



which lives, like the luli, 

 in stumps of old trees, 

 and feeds as they do on 

 decaying wood. Of this 

 vegetation, some parts 

 present themselves in 

 tolerably definite forms, 

 which have been de- 

 scribed under various 

 names ; whilst other por- 

 tions have the indefinite- 

 ness of imperfectly de- 

 veloped organisms, and 

 can scarcely be charac- 

 terized in the present 

 state of our knowledge 

 of them. With regard 

 to several forms, indeed, 

 Dr. Leidy expresses a 

 doubt whether they are 



Fungoid Vegetation, clothing membrane of stomach of parasitic plailtS, Or whe- 

 Passulus, intermingled with brush-like hairs. ther they are OUtgl'OWtllS 



of the membrane itself. 



There are various diseased conditions of the Human skin and 

 mucous membranes, in which there is a combination of fungoid 

 vegetation and morbid growth of the animal tissues ; this is the 

 case, for example, with the Tinea favosa, a disease of the scalp, 

 in which yellow crusts are formed, that consist almost entirely 

 of the mycelium, receptacles, and sporules of a fungus ; and the 

 like is true also of those white patches (Aphthae) on the lining 

 membrane of the mouth of children, which are known as Thrush. 

 In these and similar cases, two opinions are entertained as to 

 the relation of the fungi to the diseases in which they present 

 themselves; some maintaining that their presence is the essential 

 condition of these diseases, which originate in the introduction 

 of the vegetable germs ; and others considering their presence to 

 be secondary to some morbid alteration of the parts wherein the 

 fungi appear, which alteration favors their development. The 

 first of these doctrines derives a strong support from the fact, 

 that the diseases in question may be communicated to healthy in- 

 dividuals, through the introduction of the germs of the fungi by 

 inoculation ; whilst the second is rather consistent with general 

 analogy, and especially with what is known of the conditions 

 under which the various kinds of fungoid "blights" develope 

 themselves in or upon growing Plants ( 212). 



211. There are scarcely any Microscopic objects more beauti- 

 ful, than some of those forms of "mould" or "mildew," which 

 are so commonly found growing upon the surface of jams and 



