transferred to each experimental culture. 



It is consequently safe to suppose that all experi- 

 mental cultures of the same fungus were practically alike at 

 the beginning no matter when they were made. 



The four fungi used furnish for the whole study four 

 different sets of initial complexes of internal conditions. 

 Progressive variation in the internal conditions of the 

 fungus is one of the features taken in consideration, and 

 will receive attention in a later section. 



Turning to the environment, while several different 

 media were employed in certain aspects of the experimenta- 

 tion, only one (corn-raea] agar) will he considered in the 

 present paper. Special precautions were taken to have this 

 medium always the same at the beginning of all cultures, no 

 matter at v/hat time they were stpxted. The consistancy of 

 repetition showed that this aim was practically attained. 

 It was also shewn (by special evidence to be brought forward 

 later) that the unoccupied medium did not considerably alter 

 during the period of any single culture. It, therefore , 

 seems safe to assume, not only that the medium was always the 

 same at the beginning of all cultures, but also that it was 

 practically unaltered during the progress of the cultures at 

 least until it was reached and passed by the enlarging weft 

 of hyphne. That the part of the medium immediately occu- 

 pied by the developing mycelial disk, was altered by the in- 

 fluence of the fungus is, of course, highly probable, and if 

 such changes had any influence on the subsequent advance of 



13 



