374 On Parasites, Animal and VegetdbUy 



distinct layer, yellowish, elastic, very thin at the circumfe- 

 rence, and thicker towards the centre, especially of the older 

 and larger spots, which formed a kind of soil for the minute 

 plants. The adherence of this yellow layer to the membrane, 

 although close, appeared to be neither cellular nor vascular, 

 but to result from the juxtaposition of two minutely granular 

 substances having a reciprocal configuration, a mode of ad- 

 hesion this which closely corresponds with that of the epi- 

 dermis to the interior membrane of the gizzard of birds, and 

 which may be broken up in the same way. These layers did 

 not appear to have any organization. When put into boiling 

 water, and into nitric acid, they were not dissolved ; they ap- 

 peared of the nature of albumen, true false membranes, the 

 result of the irritation of the vascular and living membrane to 

 which they adhered, and which secreted them. Under the 

 larger layers of mould, the sero-mucous membrane had nearly 

 a uniform redness and thickness. Under the smaller was 

 seen, towards the centre, a vascular net-work highly deve- 

 loped, and surrounded with a zone in w^hich the vessels could 

 scarcely be perceived ; beyond this zone the vascular ramifi- 

 cations became visible, and less crowded than towards the 

 centre. The albuminous layer did not extend beyond the ex- 

 ternal circumference of the zone. 



This mould, examined by means of the convex lens and 

 microscope, appears to consist of transparent inarticulated 

 filaments, slightly, or not at all, ramified, and forming an in- 

 extricable felt closer and finer near the centre of the albumi- 

 nous layer, where they are scarcely one-eightieth of a line in 

 diameter, whilst near the external surface of the spot they are 

 nearly double the size. There everywhere exists throughout 

 this felted mass a great number of small globular or ovoid 

 vesicles, whose diameter is the same as that of the filaments, 

 which are undoubtedly the sporules ; they are white on those 

 parts of the adventitious growth which are white, and of a 

 greenish ash-colour in those places where this tint prevails. In 

 the more crowded parts of the felt the sporules fill the inter- 

 stices, while in the less crowded they are ranged in succession 

 one upon another, sometimes on one side only, at others on 

 the opposite sides of each filament. On a few of the older 



