184 SKW SUGARCANK DISEASES 



The fii-st conidinui is hoine at the tip of tho conidiophore and, 

 when full grown, is pushed to one side by the formation of a 

 second spore at the same point, and so on until a number have 

 been produced. Sometimes, instead of formino^ a second spore, 

 the apex continues cfrowth as a hypha, which may again bear 

 conidiophores (Fig. 1 3«). Unlike most members of the genus, 

 the successively formed conidia are not held together in a mucilag- 

 inous drop, but adhere merely by surface attraction and are very 

 easily dislodged. If kept free from currents of air in a moist 

 chamber, heads of 5 or more can readily be found. They adhere 

 more firmly at the base than elsewhere and if carefulty mounted, 

 after treatment with acetic acid, such appearances as those figured 

 in Fig. 7a can be observed. At first sight this suggests that the 

 spores arise near together and at the same time, as in the genus 

 Haplotrichnm, but more careful examination shows that this is 

 not the case, only one spore being formed at a time and the whole 

 apex of the conidiophore taking part in its formation. The apex 

 is pushed out b}'' growth from within the hypha to form the 

 spore, and if examined just after the latter has fallen and before a 

 second appears, the condition shown in Fig. 9 is found. In moist- 

 chamber cultures spores formed on the aerial mycelium appear 

 as shown in Fig. 8, lying in a single hyer with their long axes 

 parallel. Spore-production is extraordinarily copious, almost 

 every hypha being abundantly provided with conidiophores 

 throughout the greater part of its length. 



Germination occurs within 24 hours in many cases, the large 

 septate ajid small unseptate conidia behaving in much the same 

 manner (Fig. 11). The germ-tube is usually single and ter- 

 minal, but the septate spores may give out a tube from each end. 

 Union of two or more germ-tubes, belonging to different spores, 

 is common (Fig. 12), up to five spores having been found united 

 in this manner. One or two of the germ-tubes grow out into 

 strong hyphsD from the united mass, the arrangement being prob- 

 ably merely a nutritional adaptation. 



In culture on nutrient agar the mycelium remains white and 

 filamentous and no formation of stromata or of other types of 



