THE MOULD-FUNGI. Ill 



embraces species with very marked fermentative action. These 

 generally occur as a grey or brown felt-like mass, often 

 attaining a considerable height occasionally measuring several 

 inches in which small yellow, brown, or black spherules can 

 be distinguished by the naked eye. 



We shall describe the most frequently occurring species. 



Mucor Mucedo (Fig. 29), one of the most beautiful mould- 

 fungi, and one which occurs very generally on the excreta of 

 phytophagous animals, has a transparent white mycelium, 

 which develops numerous and delicate ramifications on the 

 surface of and within the substratum, and which, in its earliest 

 stages of development, and until the sporangia begin to form, 

 is without transverse septa, and therefore unicellular. From 

 the mycelium are thrown up single vigorous branches, the 

 sporangium-carriers ; the points of these branches which, 

 according to ZOPF, contain a reddish-yellow fatty colouring 

 matter, swell greatly, and below the swelling a transverse 

 septum is finally formed, whereby the sporangium is marked 

 off from the sporangium-carrier. The transverse wall arches 

 upwards, and forms a short column termed the columella 

 in the interior of the spherical head, whereby an inner 

 space of peculiar form (1) results. The protoplasm of. this 

 space breaks up into a number of small portions, which are 

 gradually surrounded by a membrane and rounded off; these 

 are the spores. At the same time the sporangium is coated on 

 its outer surface with small needle-shaped crystals of calcium 

 oxalate. As soon as the ripe black sporangium takes up 

 moisture, the wall is dissolved, and the spores with their 

 yellowish contents are scattered on all sides along with the 

 swelling contents of the sporangium. The columella, which 

 projected upwards in the sporangium, still remains at the end 

 of the sporangium- carrier ; this is now surrounded at its base 

 by a collar (2), the remains of the outer wall of the sporangium. 

 When the refractive spores fall on a favourable substratum, 

 they swell very considerably and send out one or two germ 

 tubes (3, 4), which quickly develop to a vigorous mycelium. 1 



In addition to this mode of reproduction, Mucor Mucedo and 



1 Many of the botanical characters stated above do not apply to M. Mucedo 

 alone, but must rather be considered as generic characters. 



