GROUP I. THALLOPHYTA: FUNGI: PHYCOMYCETES. 285 



The sporangium-wall and capillitium give the reactions of 

 cuticularised cell- wall. 



The life-history, as sketched above, varies somewhat in different 

 forms. In some (e.g. Dictyosteliaceae, Guttulineae) the mastigopod 

 stage is wanting, the spores giving rise directly to amoebae. 

 Again, the mastigopods or the amoebae may surround themselves 

 with a membrane and go through a resting-stage as microcysts ; or 

 the whole or part of a plasmodium may do the same as a sclerotium. 



Closely connected with the Myxomjcetes proper is the group of the MONA- 

 DINE^:. In their structure and life-history they generally resemble the Myxomy- 

 cetes ; but a plasmodium-stage occurs in but few forms, and then it is minute and 

 of simple structure; they are further characterised by the formation of zoocysts, 

 which give rise to ciliated or amoeboid zoogonidia. The Monadineae are parasitic. 



The Sub-Class may be sub-divided as follows : 



Division I. Monadineae: aquatic, often parasitic; usually produce zoocysts; 

 plasmodium small or wanting. 



A. Azoosporece : zoospores amoeboid ; Vampyrelleae, etc. 



B. Zoosporea : zoospores ciliated ; Plasmodiophorese, etc. 



Division II. Eumycetozoa : subaerial, not parasitic : no zoocysts ; body, a 

 plasmodium with well developed fructification. 



1. Sorophorece : zoospores simply amoeboid ; ( the cells of the plasmodium 



(pseudoplasmodium) distinct : spores not developed in sporangia, but 

 free on the surface in groups (sori) : Guttulineae, Dictyosteliaceae. 



2. Endospore<s : zoospores at first ciliated, becoming subsequently amoe- 



boid ; body, a true plasmodium ; spores developed in a sporangium with 

 a capillitium ; to this group belong most of the Myxomycetes (e.g. 

 Didymium, Arcvria, Stemonitis, Fuligo, Badhamia, etc.). 



3. Exosporece : zoospores at first amoeboid, becoming subsequently ciliated, 



and finally amoeboid again : body, a true plasmodium : spores developed 

 on the surface of basidioid sporophores ; Ceratium. 



Sub-Class III. PHYCOMYCETES. Section A. Zygomycetes. 



This section includes the following orders : 



Order 1. Chytridiaceae : simple unicellular or mycelioid forms ; 

 asexual reproduction by zoospores (and zoo- 

 gonidia). 



Order 2. Mucorinae : body, a well -developed unseptate my- 

 celium ; no motile spores or gonidia. 



Order 3. Entomophthoraceae : body, an incompletely septate 

 mycelium ; no motile spores or gonidia. 



Order 1. ChytridiaceaB. Body, a single rounded cell, or a simple mycelium ; 

 sexual reproduction known in some forms ; asexual reproduction by zoospores 

 (in sexual forms by both zoogonidia and zoospores) ; mostly parasitic, generally 



