9 



ter, if globose, and 8 to 12 by 11 to 14 /.< ifellipsoichil," contents hyaline, 

 one to several gnttulate; geruiinating readily on i>otato or in nutrient 

 agar (ri. I, 0), producing a white, immediately much branched, many 

 septate mycelium which by interweaving soon conceals the ascospore 

 and in a short time (cowpea fungus) reproduces ])erithecia, first, how- 

 ever, and usually within thirty-six hours, producing from the ends of 

 short branches or from terminal hyphae (PI. I, 7) numerous, colorless, 

 oval to narrowly elliptical conidia which are mostly 8 to 10 by 3 to 6 ^, 

 straight or curved, continuous (or occasionally one-septate after falling 

 off) and indistinguishable from those of the internal fungus (see below). 

 Mycelium on slightly alkaline meat infusion peptone agar at first pure 

 white, then grayish white (stromatic), producing immature but nearly 

 full-grown peritiiecia in largo numbers within a week of the sowing of 

 the ascosi)ore. Mycelium on steamed potato cylinders in test tubes at 



' Altogether 244 ascospores have been ineasiired directly from the plant, and all 

 of the sizes observed are recorded below in niicroua, together with the plants from 

 which taken and the nnmber of each size. P = Cowpea; AV= Watermelon; C^ 

 Cotton : 



18 X 12 W ; 17.7 x 10.2 P' ; 16 x 15 ?■ ; IG x 14.5 P' ; 15 x 12 P' ; 15 x 11.5 W ; 15 x 10 

 W ; 14.7 X 12 P' ; 14 x 14 P- ; 14 x 13.3 P' ; It x 13 P' C ; 14 x 12 P^ W C ; 14 x 11 P' 

 W ; 14 X 10 P^ W^; 14 x 9 P' W-; 13.5 x 12 P- ; 13 x 13 P' ; 13 x 12 P' W^ C ; 13 x 11 

 P' W; ISxlOP' W; 13x9 W^; 12.7 x 12 P' ; 12.5 x lOP'; 12x 12 P^s W'^ C^; 12x11 

 P^W'; 12x10 PSW'C^; 12x9.5C'; 12x9W'; 12x8 P' W"; 11.5 x 11 W ; 11. 5x 10.5 

 W ; 11.5 X 10 C ; 11.5 X 8 W ; 11 x 11 P- W* C ; 11 x 10 P2 W C«; 11x9 W C ; 11 x 8 

 W^; 10.5 X 10 P' C ; 10 X 10 P« W'"C--'; 10x9.5 C^; lOxOP'W^C^; 10x8W'; 9.5x9.5 

 W C-; 9x9 W-C^ 8x8C'. 



On the cotton most of the spores are globose, or nearly so, nearly all have a 

 wrinkled exospore, and the medium and smaller sizes prevail. On the cowpea the 

 majority of the spores are globose and wrinkled, and the larger sizes prevail. On 

 the watermelon a majority of the spores are elliptical, many are smooth and the 

 smaller sizes are the more common, as may be seen from the preceding figures. These 

 variations do not, however, appear to have any specific value, since the spores derived 

 from a single ascospore sorted out and sown on culture media may vary as greatly 

 as any here recorded. This is shown by the following set of figures derived from 

 measurements of ascospores taken from numerous perithecia grown on potato. The 

 pure culture which was used for this purpose was derived from a single wrinkled 

 ascospore taken from a typical perithecium on the cowpea. It will be seen that the 

 general tendency of these spores is to exceed the size of the original spore rather 

 than to fall short of it. They are also larger than the average of those taken directly 

 from the host plants. 



Size of 180 ascospores from a luxuriant growth on steamed potato; original spore 

 12 X 12 Jit, the number of each size is given at the right hand above ; all with wrinkled 

 exospore except a very few of the small ones: 22 x 12' ; 20 x 15' ; 18 x 14' ; 18 x 12'; 

 18 X 11' ; 18 X 10.5' ; 18x10'; 17x12'; 17xll'; 17x10.5'; 17x10'; 16.5x12'; 16x15'; 

 16x14'; 16x13'; 16xl2«; 16x11.5'; 16x11^; 16x 10' ; 15.3x 12' ; 15 x 15' ; 15x13'; 

 15 X 12.5' ; 15 x 12- ; 15 x 11- ; 14.5 x 13.5' ; 14.5 x 12.5 ; 14.5 x 12' ; 14.5 x 10' ; 14.3 x 12.5' ; 

 14xl4«; 14x13.5'; 14x13'^; 14x12.5'; 14 x 11.5'* all from one ascns; 14x11'; 13.5x13.5^; 

 13.5x13"; 13.5x12.5'; 13x13"; 13x12''; 13x 10 ; 12.5x 12.5^; 12.5x12"; 12 5x10.5'; 

 12 x 12-"- 12 X 11.5' ; 12 x 11' ; 12 x 10' smooth (7 others from the same ascus were 

 smooth); 11.7 x 11.7'; 11.5 x 11.5' smooth; 10 x 10- smooth. Thirteen of the elon- 

 gated spores were ovate ; the rest were elliptical. A very few spores were flattened 

 on the side 3 from the pressure of the ascus. 



