Dodge: Life History of Ascobolus magnificus 131 



side by side on the same hyphal branch. The hyphae of this 

 species are large and they can be traced for long distances in a 

 transparent dung-decoction agar. Anastomoses occur frequently 

 in fertile cultures near primordia, but the question of the sexual- 

 ity of the strains will not be a difficult one to determine. 



Shear (9) has studied species of the genus Glomerella and 

 made large numbers of one-spore cultures from ascospores and 

 conidia. He finds that many such strains are fertile in them- 

 selves, while others are sterile. He has grown various strains 

 and cultures together without obtaining evidence of what might 

 be called plus and minus strains. Edgerton (10), however, 

 states that he has repeatedly isolated plus and minus strains of 

 Glomerella from one-spore cultures. One strain when planted 

 alone produces some perithecia as will the other when it is grown 

 by itself, but when both plus and minus strains are grown to- 

 gether there is a dense black line of perithecia formed where the 

 strains meet. There are, however, perithecia scattered about 

 elsewhere in the culture. Edgerton was unable to find structures 

 corresponding to oogonia and antheridia ; however, he offers a 

 theory to account for the behavior of his strains. 



No sex organs are developed in the strains of Ascobolus mag- 

 nificus mentioned above except under the contact or chemical 

 stimuli of two strains in the same culture. Are archicarps 

 formed on one strain and antheridia on another? Will each 

 strain remain self sterile indefinitely? Are strains segregated 

 at the time of ascospore formation? Are there neutral strains 

 or pseudo-heterothallic strains? All of these questions remain 

 interesting subjects for further investigation. 



Summary 



1. The ascocarp of Ascobolus magnificus originates from a 

 pair of morphologically distinct primordia — a large ascogonium 

 the end of which functions as a trichogyne, and a club-shaped 

 antheridium. 



2. Papulospora magnified Hotson is an asexual stage of Asco- 

 bolus magnificus Dodge. 



3. The intrahyphal mycelium found in old cultures is simply a 

 case of " Durchwachsungen," or " cordon interne." 



