412 BOTANICAL GAZETTE [DECEMBER 
6. The endophytic fungus is probably not Pythium. The 
reproductive structures point to this genus, but the vegetative and 
certain doubtful structures point to the Ascomycetes. 
7. The habit of growth, and the appearance of the reproductive 
structures, indicate that the same species of fungus is not present 
in the two prothallia. 
UNIVERSITY OF CHICAGO 
LITERATURE CITED 
1. BrucHMANN, H., Uber die Prothallien und die Keimpflanzen mehrerer 
Europraischer Lycopodien. pp. 119. pls. 1-8. 18098. 
2. Hotrerty, G. M., The development of the eaten acne of Mnium cuspi- 
datum. Bot. Gaz. 37:106-126. pls. 5-6. 1 
3. Lyon, FLORENCE, The evolution of the sex a of plants. Bor. GAz. 
37: 280-293. 1904. 
4. SPESSARD, E. A., Prothallia of Lycopodium in America. Bot GAZ. 63: 
66-76. figs. 22. 1917. 
, Prothallia of Lycopodium in America. Bor. Gaz. 65:362. 1917. 
Pe 
EXPLANATION OF PLATES XVI-XVIII 
PLATE XVI. PROTHALLIA OF L. lucidulum 
Fic. 1.—Germinating spore, with first wall transverse; found in field. 
Fics. 2-41.—Habit sketches of various typical prothallia, some of which 
bear sporelings attached; X 2. 
Fics. 42-48.—Stages in development of archegonium; 375 
Fic. 49.—Tip of prothallium, showing five antheridia thd —— 
hairs. 
Fic. 50.—Longitudinal section of prothallium. 
Fic. 51.—Apex of same, showing acropetal succession of sex organs; 
meristem plate of cells lies just behind first initial. 
Fic. 52.—Detail of meristem and initial plate; 375. 
Fic. 53.—Single cell from meristem region; 775. 
Fics. 54-57, fig. 62.—Stages in development of antheridium and sperms; 
375- 
Fics. 58, 59.—Stages in sperm development; 775. 
Fics. 60, 61.—Mixed sex organs, reconstructed from serial camera draw- 
ings; X375« 
Fic. 63.—Longitudinal section of embryo; X85. 
Fic. 64.—Cross-section of prothallium, showing distribution of starch 
grains. 
