FUNGI IN GENERAL 113 



approach to the Algae ; and (2) the Mesomycetes and Myco- 

 niycetes, those higher Fungi with a many -celled thallus, 

 destitute of sexual organs. 



The Phycomycetes are subdivided into two distinct sub- 

 sections, which are termed the Oomycetes and the Zygomycetes. 

 In each of these the whole plant consists of a sparingly 

 branched non-septate cell, which reproduces itself sexually by 

 antheridia and oogonia, and asexually by swarm-spores generated 

 in sporangia. The Oomycetes exhibit retrogressions, which are 

 of the nature of adaptations to a more terrestrial mode of life, 

 accompanied by a progressive loss of sexuality. The families 

 of the Oomycetes are — the MonoUe2Jharideae, with antheridia 

 and oogonia in the form of sporangia, and asexual sporangia ; 

 and the Pcronosporeae and its allies, with the antheridia re- 

 duced, the oogonia as sporangia, and asexual sporangia or 

 conidia. These are united to the Zygomycetes by the inter- 

 mediate family Untomophthoreae, in which both antheridia and 

 oogonia are reduced and conjugate, and there are asexual 

 gonidia. The subsection of Zygomycetes has the sexual fructi- 

 fication in zygospores, and the asexual in sporangia and gonidia. 

 In this subsection there is a still further degeneracy in sexual 

 reproduction. Instead of the union of antheridia and oogonia 

 to produce the zygospore, there is only a conjugation of the 

 beginnings of such sporangia, because the conjugating threads 

 are only slightly swollen, and the male and female organs are 

 not to be distinguished. Asexual sporangia are present, but 

 the spores have lost their cilia, and are more decidedly adapted 

 to a terrestrial life. Five families produce sporophores any- 

 where on the mycelium, the other two bear their sporophores 

 on specialised threads which arise from the ordinary mycelium. 



The second primary group consists of the higher Fungi, in 

 two subsidiary sections : (1) the Mesomycetes, which connect 

 the higher Fungi with the Phycomycetes, and (2) the Myco- 

 mycetes, which include the Ascomycetes and the Basidiomycetes. 

 The sexual organs entirely disappear in these higher Fungi, 

 not being found even in the elementary state, whilst asexual 

 reproduction appears under a multiplicity of forms. The 

 Mesomycetes include two subsidiary groups : (1) the Hemiasci, 

 in which the fructification is by sporangia and gonidia, the 



