DESCRIPTION OF PLATE I. 



1. Mature perithecia resting on fragment of hypocotyl of an old watermelon plant 

 killed by the internal fungus. Monetta, S. C, September 9, 1895. This figure will 

 answer equally well as an illustration of the perithecia occurring on cotton or 

 cowpea. 



2. Immature ascus, with two paraphyses and a few cells of the hypothecium, 

 crushed out of a perithecium on watermelon. The smooth and still uncolored spores 

 are surrounded by granular periplasm. Monetta, S. C, September 9, 1895. 



3. Mature ascus taken from a perithecium which grew on mycelium derived from 

 the ascospore shown in G. The periplasm has disappeared and the spores are now 

 brown and have a thick wrinkled epispore. 



4. A group of immature asci crushed out of a perithecium on cowpea. 



5. Ripe ascospores of the watermelon fungus highly magnified. 



6. Germinating ascospore, cowpea fungus. Agar-plate culture. James Island, 

 S. C, August 22, 1895. 



7. Conidia-bearing mycelium developed from the ascospore shown in 6'. 



S. Three of the same conidia more highly magnified, one germinating. These 

 conidia are identical in appearance with those produced inside of the vascular sys- 

 tem of the still living stems. (See Plate II, 11.) 



9. Surface or dry-air conidia of the cowpea fungus. These were taken from the 

 conidia beds shown in 11 and 13. 



10. Fragment from a cross section of the living cowpea stem, about 2 feet from 

 the ground, showing a group of vessels infested by the fungus (c, cambium; x, xylem; 

 p, pith), imbedded in paraffin, cut on the microtome, and stained for many hours in 

 acid haematoxylin. This picture represents about one-thirtieth of the vascular ring, 

 nearly all of which was occupied in the same manner. The cortical parenchyma and 

 the bulky pith were still free from the fungus, as is always the case in this stage of 

 the disease. Later the fungus pushes through to the surface, as shown in 11 and 12. 

 James Island, S. C, August, 1895. 



11. Surface of dead stem of cowpea, showing rows of conidia beds. The vessels 

 of such plants are always previously occupied by the internal fungus, as shown in 

 10. The row-like arrangement of the conidia beds is due to the fact that the fungus 

 comes to the surface along lines of least resistance— i. e., through parallel rows of 

 parenchyma cells separating the strands of tough bast fibers (stereome). x2. 

 James Island, S. C, August, 1895. 



12. A similar fragment of dead stem of the cowpea more highly magnified. X 10. 



13. A tube of boiled rice overgrown by the mycelium of the watermelon fungus 

 (Ftisarium niveum). Culture No. 4, October 8, 1895. Painted October 28, 1895. This 

 culture was bright blue on the start, 2 c. c. of violet litmus water and a few drops of 

 a saturated solution of sodium carbonate (t. 25° C.) having been added to it. The 

 same brilliant colors may be obtained, however, as already stated in the text, without 

 use of litmus — i. e., by simply cultivating the fungus for a few weeks on rice boiled 

 in distilled water — and this figure will answer equally well for such cultures. High 

 up on the walls of the tube (above the rice) the fungus is white. 



14. An incipient perithecium developing on mycelium produced by the ascospore 

 shown in 6. 



With exception of 10, 11, and 12, which were painted under my supervision by Mr. 

 John L. Ridgway directly from the specimens, and 13, which was j)ainted in the same 

 way by Miss D. G. Passmore, the figures are from my camera drawings. 1 was trans- 

 ferred to the plate and painted by Miss Passmore. The rest of the work was done 

 by Mr. Ridgway. Where no measurements are given they are included in the plates 

 or may be learned from the text or from other figures of the same sort in which they 

 aie given. 

 54 



