Dodge: Life History of Ascobolus magnificus 129 



there were no fruit bodies although papulospores could be found 

 in all of the cultures. The last three cultures have not produced 

 ascocarps. The following table shows cultures of which a record 

 was kept in testing out the strains. Many others were made 

 simply to obtain primordia for purposes of study. 



It is clear that at least for these strains each is sterile by 

 itself or strains 2, 3 and 5 are sterile (in the combinations tested) 

 when placed together, as are strains 1, 4 and 7, but a combination 

 of any one of either group with any one of the other group pro- 

 duces a fertile culture. I have since obtained ten new strains 

 from germinated ascospores. These strains fall into two groups, 

 two of which are like the original No. 2 and eight are like No. 4. 



The use of sterilized fresh horse manure in jelly glasses or in 

 milk bottles is preferable when it is simply desired to ascertain 

 whether single strains ever become fertile because this is the 

 natural substratum and the ascocarps reach a large size whenever 

 the culture is fertile. On the other hand, when the fertility of 

 two strains in combination is to be tested one of the transfers 

 may not grow and it is then impossible to draw any conclusions 

 whatever from negative results. Whenever papulospores are 

 found it is certain that one strain has developed a mycelium, 

 while the other may not have grown at all. On the other hand, 

 plate cultures obviate this difficulty since it can be seen (within 

 24 hours) whether either strain has begun to grow, and if one 

 has not a reinoculation can be made. No single strain culture 

 on dung is reported sterile in the above table where an examina- 

 tion was not made to find papulospores, thus proving that the 

 inoculation was successful. Twelve-inch test tubes containing 

 the dung decoction agar are most satisfactory for keeping pure 

 cultures for a long time. Ascocarps up to a centimeter in diam- 

 eter have been grown in these large tubes, while I have not been 

 very successful in growing ascocarps in small test tubes. 



Not all of the possible combinations of strains 1, 2, 3, 4, 5 and 

 7 have been tried in these different ways, because the first thing 

 desired was a combination that was sure to produce primordia 

 for purposes of study. Strains 2 and 4 were chosen for the most 

 extensive tests, and it can be said that each is sterile by itself and 



