DESCRIPTION OF PLATE III. 



1. Microconidium from the interior of a melon stem, germinating after 7 hours in 

 agar. 



2. Th« same conidium, after 24 hours in agar, showing numerous branches and. the 

 abstriction of new conidia. Under favorable conditions conidia are formed very 

 rapidly. Three hours after this drawing was made this mycelium had given rise to 

 40 free conidia and 30 more were in various stages of growth. 



3. Formation of microconidia of the watermelon fungus in an agar plate culture. 

 This hyplia end was under continuous observation for two hours and eighteen min- 

 utes, during which time two spores were developed and abstricted and another 

 begun. Room temperature, 27° C. The formation of conidia was carefully followed 

 in a number of other cases. Under the most favorable conditions of temperature 

 and food supply only forty-five minutes intervened between the pushing off of one 

 conidium and the formation and abscission of another. Usually, however, fifty-five 

 to sixty minutes was required. 



4. Mycelium and conidia of the melon fungus from a young agar culture. This 

 was one piece of mycelium, broken in the drawing at the place marked x for con- 

 venience of representation on the plate. Mycelium and conidia vacuolate, all 

 formed in the agar, only sterile hyphie ends projecting into the air in this early stage 

 of growth. Two spores germinating. This figure well illustrates the waythehypha 

 end throws oif a few conidia, passes into a vegetative condition, and elongates for 

 a time, with formation of septa, and then once more ceases to elongate and becomes 

 sporiferous. Monetta, S. C, July 4, 1894. 



5. Microconidia of the melon fungus from an agar plate, showing the variability 

 in size. Two spores germinating. 



6. Conidia and torulose mycelium from a culture of the internal watermelon 

 fungus {Fusariuni niveian) 27 days old. 



7. Fragment of mycelium from the same culture as 6. 



8. Fragment of mycelium from a culture of the internal cotton fungus (Fiisarium 

 vasinfectum) 25 days old. For comparison with 7. 



9. Mycelium and microconidia of the cotton fungus {Fusarium vasinfectum), culti- 

 vated from the interior of a diseased cotton stem received from western Georgia. 

 From a pure white culture 25 days old. For comparison with 3 and 4. 



10. Conidia of the cotton fungus from a culture 25 days old, derived from the 

 internal or microconidia. For comparison with 11. 



11. Macroconidia and microconidia of the watermelon fungus from a pure cul- 

 ture 5i mouths old, on sterilized horse dung. The mycelium which bore these 

 spores was derived from a spore of the size and shape of the largest here shown. 



12. Chlamydospores of the melon fungus. Several germinating. From a pure 

 culture 5i months old, on horse Jung. This culture was derived from a lunulate, 

 ^everal-septate, external conidium. In mass these chlamydospores were brick red, 

 and their contents was considerably denser than has been indicated by the engraver. 

 At 11 a. m., when the examinations began (in water), there were no germinations; at 

 4.30 p. m. there were many. In the same tube with these chlamydospores were 

 conidia of all the sizes shown in 11, the small spores being much more numerous 

 than the large ones. 



Figures drawn by the author and engraved on wood by L. S. Williams. 

 58 



