150 PLANT LIFE. 



and bearing the same relation to chlorophyll-producing 

 Phanerogams that fungi do to chlorophyll-producing algae. 



The evidence in support of the idea that the fungi are 

 derived from the algae by retrogression, is the close morpho- 

 logical agreement of both vegetative and reproductive parts 

 presented by certain sections of the two groups ; for example, 

 in the sub-division of fungi called Phycomycetes, the vegetative 

 portion frequently consists of a long, aseptate, variously 

 branched cell or hypha, similar to the vegetative portion of 

 such algal genera as Vaucheria ; in the reproductive portion, 

 asexually formed ciliated zoospores occur in Pythium, 

 Saprolegnia, Cystopus, etc., while oogonia containing one 

 or more oospheres fertilized by motile antherozoids occur 

 in Monoblepharis. In a second group, the Mucorini, the 

 sexual mode of reproduction is effected by the conjugation 

 of two similar branches, as in the Conjugate, the resulting 

 zygospore becoming invested by a thick cell-wall, and 

 forming a resting-spore. Many species belonging to the 

 Phycomycetes are aquatic, being parasitic in the tissues of 

 aquatic plants or animals. 



In numerous species two or more modes of reproduction 

 are known : in the Phycomycetes, or algal -like fungi, one form 

 is usually sexual, the remaining one or more asexual. In 

 some instances both forms of reproductive bodies are 

 produced by the fungus at the same time, but as a rule the 

 asexual form appears first, the sexual or at all events more 

 highly evolved form being developed later, and either on 

 the same mycelium as the asexual form, or on a distinct 

 individual springing from the asexually produced repro- 

 ductive bodies. 



True alternation of generations as understood in the 

 higher Cryptogams is absent from the fungi where either the 



