532 FETCH : 



are not organically connected. I have on several occasions 

 noted the appearance figured by Cobb (see p. 523), but 

 have always been able to determine that the spores were not 

 united. 



When first extruded, the microconidia are liyaline, and 

 almost exactly rectangular in outUne. Their length is usually 

 S-12 '^, but I have measured one 32 \j. long in a chain in which 

 none of the remainder exceeded 12 \i.. Their breadth depends 

 upon the apical diameter of the conidiophore ; usually it is 

 5 [I, but sometimes only 4 \x, and rarely 6 [j.. Subsequently 

 they become oval, and gradually darken until they are 

 fuliginous, or greenish black, but tliis change in colour is 

 much slower than in the case of the macroconidia. In hanging 

 drops, the macroconidia have usually been produced and have 

 changed colour before the change of the microconidia has 

 occurred. The spores which remain permanently within the 

 conidiophore darken much more rapidly than those which 

 have been extruded. Also, if the hyaline microconidia are 

 transferred to a hanging drop of water, the colour change is 

 still further delayed : in one such instance, only fifty per cent, 

 of the spores changed colour in fourteen days. It would 

 appear from this that the colour change is dependent upon 

 some product of the mycelium. No hyaline conidia are to be 

 found in a flask culture six days old. 



When the hyaline conidia are sown in a hanging drop of 

 water, some of them put out a germ tube, usually from one 

 corner, but this seldom grows longer than 5 to 10 jx. If sown 

 in sugar cane extract, the subsequent development is exactly 

 the same as in the case of the mature conidia. 



When fully mature the microconidia are greenish-black or 

 brownish-black, oval, usually 11-14 x 7-9 ^Ji. ; some are larger 

 than this ; and sometimes the smallest become spherical, 5-7 [l 

 diameter. 



The Macroconidia. 



About twenty-four hours from the time of sowing the spores, 

 the macroconidia begin to appear. At first the macroconidio- 

 phores are produced with the last of the microconichophores, 

 and on the same hyphse, but later all the conidiophores 

 produced are macroconidioj)hores. They are short, lateral 



