218 AGRICULTURAL EXPERIMENT STATION. [Jan. 



the end of the first day (fig. 9). They may continue to 

 grow for about two days, in which time the germ tulje may 

 become several times as long as the greater diameter of the 

 spore. If no nourishment l)e obtainable, growth ceases and 

 death follows. If, however, nourishment be provided in the 

 form of an infusion of prunes, for instance, the development 

 of the germ thread is very rapid, and the entire culture drop 

 is filled by a mat of strong and branching threads. The 

 difference in development due to absence or presence of 

 nourishment may be seen by comparing figs. 9 and 10, 

 which represent spores after one day's development under 

 these opposite conditions, respectively. Vigorous branches 

 of the mycelium grow upward into the air and downward 

 into contact with the glass slip supporting the culture. 

 No traces of spore formation could ever be detected on 

 the aerial threads, although carefully sought for. On the 

 l^ranches which come in contact with the glass are produced 

 in all nourished cultures, and very abundantly, certain 

 structures characteristic of this and related species of fungi, 

 and known as attachment organs. These organs a[)pear to 

 be formed whenever branches of a growing mycelium come 

 in contact with firm unyielding objects. They are produced 

 by the rapid and more or less exactly dichotomous branch- 

 ing of a thread, which, at the same time, becomes much 

 stouter and richer in protoplasmic contents than before. 

 The short and densely aa'o'regated branches form a thick 

 tassel, Avhicli becomes attached by the free ends of its 

 branches to the substratum (fig. 11). At this time these 

 organs are readily recognized by the naked eye as small 

 darker spots on the glass of the culture sli)) or vessel. A 

 day after its complete development one of these organs 

 shows signs of degeneration. Its dense contents beofin to 

 1)ecome watery and to disappear, and by the second day 

 there is left little but the empty outer walls, enclosing a 

 nearly or quite continuous cavity (fig. 12). The possible 

 or probable significance of these peculiar structures may be 

 discussed later. Slide cultures of spores in prune infusion 

 or similar fluid medium rarely yielded anything besides 

 mycelium and attachment organs ; 1)ut occasionally a small 

 sclerotium is developed. The vegetative development on 



