MUCORIN^ AND ASCOMYCET^E. 149 



called sporangia, the protoplasm of which, without being rein- 

 forced from that of another cell, proceeds to break up into 

 the elements of new individuals, often called, when motile, 

 swarm-spores. Both forms of reproduction are usually mani- 

 fested by each species. The degradation of the fungi consists 

 in the gradual loss of the faculty of sexual reproduction, so that, 

 in the most extreme species of the group, it does not appear at 

 all and only asexual reproduction can be traced. We shall now 

 describe a few of the typical forms of these lower fungi which 

 are often met with in bacteriological work. 



Mucorinae: Mucor Mucedo. This form occurs especially in the 

 putrefaction of horse dung and also in other putrefactions. To 

 the naked eye it appears as a white or brownish-white mass of 

 fine filaments, from which, here and there, rise special filaments 

 often several inches long, having at their terminations spherical 

 brown swellings, the reproductive elements. Microscopically, 

 the plant consists of branching non-septate filaments. Such a 

 structure is called a mycelium. The non-sexual is the commonest 

 form of reproduction (vide Fig. 61, A4). One of the filaments 

 grows out, at its termination a septum forms, and a globular 

 swelling (the sporangium) appears. This sporangium possesses 

 a definite membrane. Within it from the septum grows a club- 

 shaped mass of protoplasm called the columella, to which are 

 attached the swarm-spores formed from the breaking up of the 

 rest of the protoplasm. When ripe the brood cell bursts, the 

 brown swarm-spores are cast off, and from each a new individual 

 arises. Under certain circumstances sexual reproduction occurs 

 (vide Fig. 61, A 1-3). Two filaments approach each other, and a 

 small piece of the protoplasm of each being cut off by a septum, 

 these parts coalesce. A zygospore is thus formed from which 

 a new filamentous individual arises. 



Ascomycetae : Oidium Lactis (Fig. 61, B). This is a common 

 organism in sour milk and sour bread. It can easily be culti- 

 vated on gelatin where the colonies appear to consist of fine 

 white filaments radiating from a centre. Microscopically here 

 and there the filaments (which may be branched) are broken 

 up, especially at the ends, into short, rod-shaped or oval seg- 

 ments, often referred to as the oidia. These behave like spores. 

 Non-sexual reproduction also takes place by the formation, within 

 certain special sporangia in the filament called asci, of a definite 



