86 



in morphological characters, and was of little differential value. On 

 either washed agar or plain agar there was excellent linear growth but 

 poor color and little conidia-production. Bean agar gave too luxuriant 

 vegetative growth. Brazil-nut agar was useful for the development 

 of white mycelium for use in nutrition studies and for study jof^proteoly tic 

 action. The other agars used showed no special features of value. 



RICE AND SIMILAR SUBSTANCES AS MEDIA, WITH SPECIAL 

 NOTE OF COLOR PHENOMENA 



Rice in test-tubes. Rice was prepared in the customary way, by placing 

 it in test-tubes to a depth of one centimeter, adding enough water to 

 stand 1 cm. above it, and then autoclaving. This medium, so useful in 

 the study of many fungi, notably of Fusarium, proved very interesting 

 here. At the expiration of about two weeks from the time of inoculation 

 generally the most profitable time for first observation three zones or 

 regions could usually be recognized: (1) the region recently invaded by 

 the fungus, which I designate as the recent region; (2) the region first 

 invaded, which had assumed nearly its final appearance, and which I call 

 the old region; and (3) the region midway between 1 and 2, which I shall 

 call the median region. 



Each of these regions showed characters of its own. Within all of 

 them, but particularly in the old and in the median regions, there were 

 three points to observe: (a) the places where the rice grains came in contact 

 with the glass, which places I call contact; (b) the spaces between rice grains, 

 at first filled by water, which I call the interstices; and (c) the line between 

 interstices and contacts, which I term the border. Usually the fungus 

 grows down into the interstices, consumes their contents, and fills the 

 remaining space more or less completely with mycelium. Penetration 

 of the contacts is very slow and may not occur at all, therefore they are 

 usually but slowly discolored by the passage of various chemicals into them. 

 The border is the region of greatest development, and often presents a 

 sharp, distinct line of pronounced character. It is the contrasts furnished 

 by the contacts, interstices, and borders, often attended by the develop- 

 ment of beautiful and vivid colors, that give to these cultures their strik- 

 ing appearance. In addition to these characters the final appearance of the 

 rice column should be noted. It is sometimes digested away in characteristic 

 manner. The development or absence of sclerotia is also noteworthy. 



H. No. 1, in rice test-tubes, at two weeks, gave, in the recent region, 

 salmon-colored interstices, contacts, and borders; in the median regions the 



