28 



dauce of microconidia, hut tliere n-as not a shu/le perithecium. Up to 

 the ninety-second day, when the exj)erimeut was lost, not a single 

 perithecium had formed on this alkaline agar. No contrast could be 

 more striking, except possiblj' the following : 



(2) On the best medium known to the writer for the abundant and 

 rapid production of perithecia, viz, potato steamed in distilled water, 

 the development of perithecia was altogether prevented by the addi- 

 tion of carbonate of soda. A copious stroma was formed, and there 

 was an abundant development of microconidia, hut in 76 days there 

 teas no appearance of perithecia. These cultures were on potato cylin- 

 ders steamed in test tubes with 2 c, c. of water and 1 c. c. of a satu- 

 rated solution of sodium carbonate. A second set of tubes was 

 prepared in the same way, but received less alkali (about one-half as 

 much). For comi^arison, cylinders cut from the same tuber were 

 steamed in a strong malic-acid water. The acidified cylinders were 

 white; those steamed with the alkali were uniformly brown. The 

 three sets were inoculated at the same time (December 16) copiously 

 with ascospores from the same culture. On the fourth day there was a 

 much better growth in the acid tubes; growth in the alkaline tubes 

 was sparing and only to be detected with a hand lens. 



On the tenth day the fungus in the alkaline tubes had made a pure 

 white but very restricted growth, varying iu area from one-half to IJ 

 qcm. In the tubes which had received the least alkali there was a 

 stroma and an abundance of microconidia, but in none of the four was 

 there any trace of perithecia. On the malic-acid substrata the fungus 

 had now entirely covered and hidden from sight the whole of the large 

 potato cylinder with a wrinkled stroma. This bore in each of the four 

 tubes several thousand perithecia, which were already rose color or 

 bright coral red. The acid appeared to have favored rather than hin- 

 dered their formation. On the seventeenth day the entire surface in 

 each of the acul tubes was so thickly studded with bright coral-red 

 perithecia that there seemed to be no room for any more. These 

 tubes were now no longer acid, although strongly so when inoculated. 

 Each of the four cylinders was tested. There was no trace of acid 

 reaction in two, and in the other two it was extremely faint and limited 

 to the bottom part of the cylinders, which was the last part to be 

 invaded by the fungus. It would therefore appear that the fungus 

 consumed it as food. On this date, on each of the alkaline cylinders, 

 the fungus had formed a stroma, which was gray-white, wrinkled, and 

 mealy from the jiresence of great numbers of microconidia. In the 

 tubes which received the most alkali the stroma covered about one- 

 fourth of the surface and there were no perithecia. In those which 

 received less alkali it covered about four-fifths of the cjdinder in one 

 tube, and only about one-twentieth in the other. In both of the latter 

 perithecia were forming in small numbers, and were first visible on the 

 fifteenth day. The tube containing the smaller stroma was now opened 



