1891.] The Comparative Morphology of the Fungi. 1063 
threads, some of which bear sporangia like those of Mucor 
l (fertile threads), while others become rhizoidal (sterile threads). 
! In Mortierella these sterile threads become woven together to 
f form a dense capsule about the base of the fertile ones, which 
are long and stout. Itis easy now to suppose the fertile threads 
reduced in length until the sporangia at. their ends are withdrawn 
within the capsule, and just this condition is found in Theleġolus 
Stercoreus, whose fruit body contains a single many-spored 
sporangium. From this condition a further step leads to that so 
familiar in the genera Spherotheca and Podosphzra, in which 
the indefinite sporangium of Thelebolus has become a well- 
defined ascus, while the capsule is essentially unchanged. The 
simplest of the Carpoasci are the Gymnoasci, which have a well- 
marked ascus, but whose capsule consists of very loosely entan- 
gled hyphz. Another line may be traced from some Choane- 
phora-like form, with sporangia and conidia, through the new 
plant described as Ascoidea rubescens, which produces ascus-like 
sporangia and conidia, to the numerous conidia-bearing Ascomy- 
cetes, 
Having seen how all of the primary fruit forms of the higher 
fungi, the ascus, the conidium, and the basidium, are derivable 
from the simple sporangium of thé Phycomycetes, we may sum- 
marize the whole graphically as follows: 

id 

Sporangium. 
(Mucor.) 

Sporangium. Sporangiolum. 
(Thamnidium.) — s 
Sporangium: Closed Spor'm.=Conidium. 
(Rhizopus. \ peo erring 
(Mortierella. ) 
; Ascus-like Spor'm, A.scus-like Spor'm. Basidď’ -like Conidiophore. 
(Thelebolus.) and Conidium. (Ustilagineæ.) 
(Ascoidea.) 

N 
Ascus. . ` Ascus and Conidium Basidium. 
(Ascomycetes.) (Ascomye with conid ) (Basidiomycetes.) 

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