11 



trace of peritliecia, altbougli from time to time special ettbrts were made 

 to liiul a substratum which wouUl lead to the production of i)erithecia. 

 This is the strain of fungus which has proved so actively parasitic 

 in the hands of the writer. 



On agar and on potato the peritheciaof the cowpea fungus showed a 

 distinct tendency to be larger than on the host plant, owing probably 

 to extra good nutrition. The diameter of the largest on nutrient agar 

 ranged from 320 to 376 //. The diameter of the largest on potato ranged 

 from 3G0 to 410 //. The perithecia on the potato were exceedingly 

 numerous, sometimes as many as 5,000 developing on an urea of not 

 more than 15 or 20 square centimeters. They were much less numer- 

 ous on the slightly alkaline meat infusion peptone agar, and ripened 

 and developed their bright red color much more slowly. On certain 

 other media the peridium remained nearly colorless or the perithecia 

 failed altogether to develop, although the fungus was under the same 

 conditions except as to the substratum. Numerous cultures on a great 

 variety of media have shown that the presence or absence of a stroma 

 is entirely a matter of the substratum. 



:So attempts have been made to grow the ascospores from the similar 

 I)erithecia which have been discovered on the dead stems of cotton and 

 watermelon. No perithecia ever developed in any of the cultures made 

 from internal or external conidia taken from the cotton or watermelon. 



CONIDIAI. FRUITS. 



(1) Microconidin. (Cephalosporium stage).— Colorless, oval to nar- 

 rowly elliptical, straight or slightly curved, non-septate spores, 4 to 25 

 by 2 to //, borne singly one after another (PI. Ill, 3) on the ends of 

 short branches of a mycelium, which fills the water ducts and interior 

 parts of the liviny stem (melon, cowpea) with a dense growth that is 

 pure white when seen in mass in the stem or when cultivated out on 

 alkaline meat infusion peptone agar, or on other alkaline media, even 

 rice: conidia frequently 1 septate (or rarely 2-septate) after abscission, 

 in cultures often remaining in a little group n round the end of the 

 stationary couidiophore or becoming scattered when the latter elongates 

 after having produced a group of spores, as is frequently the case 

 (PI. 1, 7, PI. Ill, i), aerial or submerged {Fusarimn vasinfeetum Geo. F. 

 Atkinson, described from cotton and okra; Fvsarium nivenm'Erw.F. 

 Smith, described from watermelon). None of the large, lunulate, 3 to 

 5 septate spores describ( d below have ever been observed in the vessels 

 of any of the host plants or submerged in fluids or solids. 



(2) Macroconidia (Fusarium stage).— Lunulate; 3 to 5 septate spores, 

 30 to 50 by 4 to // (PI. I, 9; PI. II, 7; PI. V, 5), borne on the surface 

 of dead stems in immense numbers on innumerable small, oval or 

 hemispherical conidia beds which arise from the internal mycelium 

 and consist of compact, irregularly branched, short conidiophores. 

 Examined in water the single spores are nearly colorless; in mass they 



