THALLOPHYTA— FUNGI 77 



the myxomycete is at some time characterised by this behaviour 

 which recalls the condition of the form of animal known as the 

 Amoeba. While the separate masses are still motile they can 

 multiply by cell-division, which has been ascertamed to be pre- 

 ceded by karyokinesis. Ultimately the amoeboid masses collect 

 into & ijlasmodium, without fusion of the nuclei, so forming a 

 kind of coenocyte {fig. 829, a). Like the constituent cells, the 

 Plasmodium can creep about by means of pseudopodia. A 

 familiar example of this fungus is the so-called ' Howers of tan ' 

 {Etlialium), which is found in the form of jelly-like lumps in 

 tan yards. 



The Plasmodium in time comes to rest, and gives rise to 

 one or more sporangia. In the latter case it divides into as 

 many pieces as sporangia. The whole of the mass shrinks up 

 into a rounded body which shows differentiation into a hardened 

 outer portion or wall, and an inner mass which gives rise to 

 spores. The substance of the inner portion produces a peculiar 

 protoplasmic network of filaments, the capilUtlum {fig. 829, c), 

 among which are formed the spores, these being furnished with 

 a cell-wall which each secretes independently. Sometimes the 

 sporangium is stalked, sometimes not ; occasionally' a protrusion 

 of the stalk into the sporangium forms a kind of columella. 

 The spores are, after a time, liberated, or scattered by the elastic 

 capihitium, and give rise to the amoeboid masses already 

 described. 



Sub-Class III. — Phycomycetes. 



In this group we have the only undoubted cases of sexual re- 

 production, which may take the form of conjugation, or fertilisa- 

 tion, thus giving rise to two sections, the Zijgomgcetes and the 

 Oomycetes. In both groups the mycelium is miseptate, or in- 

 completely septate, being a coenocyte. 



Zygomycetes. — The form most generalh' known in this group 

 is the common mould, Mucor Mucedo,iova\^ generall}- on dung 

 and other decaying organic matter. The spore gives rise to a 

 copiously branched mycelium, which ramifies very freely in the 

 substratum. When well established it throws up aerial branches 

 which terminate in globular heads or gonidangia. A septum is 

 formed close to the apex of the hypha, cutting off a small head 

 which grows and becomes globular. The lower cell grows also, 

 and projects into the swollen portion, forming a columella {fig. 

 823, m). The contents of the terminal cell break up into a 



