108 MISSOURI BOTANICAL GARDEN. 



fruiting bodies are usually borne at or above the surface of 

 the medium upon which it is cultivated. The following is 

 a resume of the cultural characters of the funmis : — 



Mycelium. 



The spores of the fungus germinate in a very short time, 

 usually a few hours, and in thirty-six hours small white 

 colonies are visible upon the surface of agar media. The 

 first mycelium that forms is rather sparse, but thickens as 

 the colony grows older. Two types of conidia are borne 

 on the fertile hyphae, which are formed in a short time 

 after germination of the spores. These are the micro- 

 conidia (pi. 12, f. 1, 2, '3), which are found very numerously 

 in all parts of the mycelium, except in the newest growth, 

 and the macroconidia (pi. 12, f. 4, 5), which are found 

 sparsely only in the older portions of the mycelium. 

 Chlamydospores are formed abundantly in all the older 

 portions of the colony about the time the growth of the 

 mycelium is checked by a limitation of nutrition, being 

 formed usually with or a little later than the macroconidia. 

 The anastomosing of filaments is quite frequent (pi. 12, 

 f. 8). 



MlCROCONIDIA. 



Microconidia are formed in great numbers on various 

 vegetable media, such as agar media made with plant decoc- 

 tions. They are usually borne on hyphae which branch 

 alternately from the mycelium. They are formed by the 

 n! /friction of the ends of hyphae, and where they are not 

 disturbed by air currents or some sudden shock, they 

 adhere to each other side by side in clusters which assume 

 a form of fruiting resembling Cephalosporin (pi. 12, 

 f. 3). These microconidia are at first one-celled. A sep- 

 tum is often formed before the spore becomes detached 

 from the hypha, and later many of the one-celled conidia 

 that have fallen off form septa. The two-ceiled form 



