[Vol. 2 

 366 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



1. Tendency to late copulation of gamogenic branches, so that 

 archicarp becomes large and many-nucleate, or tendency to 

 elongate, or both, 



2. As it elongates tendency to septation, first a single terminal cell 

 ("trichogyne"), and later longer and multiseptate "trichogyne," 

 or rather sterilization of terminal portion of archicarp. One of 

 the early tendencies in connection with elongation of the archi- 

 carp may have been the origin of a receptive terminal portion 

 under chemotactic or similar stimulation ; such a condition sug- 

 gested in Cystopus. 



3. This made the passage of antheridial nuclei increasingly diffi- 

 cult, and resulted in early tendency to sterilization of anther- 

 idium or failure to function because of functionless condition of 

 "trichogyne." Led in many cases to modified sexuality by dif- 

 ferentiation of sex among nuclei in ascogonium, vegetative cells, 

 or ascogenous threads. 



4. Progressive tendency to multiplication of spores by postpone- 

 ment of nuclear fusion and spore formation ; conjugate division 

 of sex nuclei, and multiplication of the specialized structures 

 (asci) in which spores are formed, so that spore formation and 

 distribution is extended over greater period of time. This most 

 advantageously attained by sprouting of zygote (ascogone), 

 branching of threads, and terminal formation of specialized asci. 



Diverging lines from Gymnoascus and Monascus-liikQ an- 

 cestors or related prototypes in which asci are irregularly 

 arranged but associated in groups with imperfect envelope. 



1. A line with interwoven asci, Plectascales as a highly specialized 

 lateral group, with Gymnoascaceae at base. Aspergillaceae a 

 progressive line, with Perisporiales an offshoot, or Perisporiales 

 direct from Monasciis-\ike ancestors. 



2. Elaphomycetaceae, asci interwoven in groups but separated by 



sterile walls. 



3. Pezizales, asci remaining in groups not interwoven in mycelium, 

 but spaced by sterile threads (paraphyses). Pyronema repre- 

 sents one of the generalized, lower forms. The Helvellales, etc., 

 are probably derived from the Pezizales. 



4. The Microthyriales^ have usually been placed among the Peri- 

 sporiales with which they have little in common. I believe they 



^Recent studies by several authors, particularly by von Hohnel ('10) and 

 by Theissen ('12, '13, '14) have greatly increased our knowledge of these interest- 

 ing fungi, partly by the discovery of new forms but especially by uncovering 

 many forms from the clouded situation in which they have been placed for lack 

 of an adequate study of their structure. 



