MUCOR. 123 



ment is not within the spores, but forms a powder, amidst which they 

 lie. Mycelium forms an interlacing network, as in other species. 



A. fumigatus. On Potato, &>c. — A slate-blue coloured growth, 

 rapidly extending as a thin paper-like pellicle over the surface of the 

 nutrient soil. If its lateral extension be checked, the layer becomes 

 crenated, being thrown into a series of irregular deep furrows and 

 ridges. Its colour deepens with age to a bronze brown. 



/// Gelatine. — Forms coloured nodules at surface, colourless spherules 

 in centre of jelly ; in the latter no spores are produced. 



In Liquids. — Floats on surface as a slate-blue velvety layer. 



Microscopically. — As other species, except that fine granules around 

 spores have a slate-blue colour. 



A. glaucus. — Precisely similar to above, except that on solid 

 media it does not form a crenated layer, but remains flat ; is soft and 

 velvety, and of a light brown colour. The colour due to powdered 

 granules on the basidia, as in other species. 



A. flavescens. — Only differs from above in possessing a light 

 yellow colour, tinged with light green, and its surface, when grown 

 on solid media, becomes gently undulating. 



A. nigrescens (Fig. 28, p. 69.)— A growth of a deep rusty black 

 colour ; surface velvety, not crenated, when grown on solid media. 

 Colour due to dark brown pigment granules, lying as fine powder 

 around spores. Pigment soluble in ammonia. Other characters as 

 in three preceding species. 



A. fulvus. — Growing precisely like A. glaucus, but of a coffee 

 colour. 



GENUS MUCOR. 



A group of species having a branched, colourless mycelium, the 

 terminal twigs of which carry spherical sporangia. These sporangia 

 are hollow receptacles, in which the spores are contained, like small- 

 shot in a bomb. Differences of species are recognised by the colour 

 of the sporangia, and by some peculiarities in the mode of growth of 

 the mycelium. From a large list of known species the following are 

 selected as those most commonly met with : — 



Mucor mucedo. On Potato, ore. — A silky white growth, consisting 

 of a tangled tuft of glistening hairs, attaining a height of from one to 

 one and a half inches. At the ends of these fibrils are rounded 

 glistening bodies, at first white, but soon becoming brown, and then 

 an intense black. These are the sporangia. 



In Gelatine. — Grows rapidly throughout jelly as a glistening net- 

 work of fibrils, the typical black sporangia only being produced when 

 it reaches the surface. 



