155 



isms to search for differences, does not seem a promising line of research 

 because negative evidence would be valueless, while positive evidence 

 would be obtained only most rarely, even though saltation is very com- 

 mon. Since, even in my most rapidly saltating strains, changes occur in 

 only 1 out of 5,000,000 cells, and re-isolations from soils would give col- 

 onies from single conidia only, that is, from a small group of cells, the 

 evidence of saltation by this method of investigation could reasonably be 

 expected only once in several thousand platings. 



NOTES CONCERNING SELECTED INDIVIDUAL SALTANTS 



Unless otherwise noted the permanence of the saltant characters 

 were tested by repeated transfers. Colony-characters were determined 

 on corn-meal agar; measurements of conidia and other conidial characters, 

 under standard conditions. 



Ml. Origin slightly zonated (PI. XXIII, 1), few conidia. Ml-1 grew 

 faster than its origin; ratio, 6.5:8; characters maintained through several 

 transfers. 



M6-1. Much like Ml, but with decided difference in conidial breadth 

 (Graph 70, Fig. Q). 



M8. Growth slow; conidia few, pale, and thick (Fig. Q) ; septa 

 few. The squarish cells very striking; differences apparent also on green- 

 wheat agar. 



M12-3. Quite distinct in septation and breadth. As to conidial length, 

 see Graph 121, Fig. Y, and data. 



Ml 7-3. A distinct variant in thickness, septation, and shape. As to 

 conidial length, see Graph 138, Fig. Y, and data. 



M26. (See page 143, and PL XXX and XXXI.) 



M35. Characterized by its very short conidia (see page 141 and 

 Fl. XXVI, c). 



M36. Derived from a single-conidium culture; conidia thick. 



M38. The colony had much aerial mycelium and was quite white, 

 though a shade of black from the surface-agar showed through ( PI. XXVII) . 

 It continued through many transfers as a pale form with scant conidia. 



M53. (PI. XXX). Very different from its origin, being covered with 

 much loose, white, aerial mycelium, rendering the whole colony white and 

 flurry in appearance, while the original colony was neither white nor fluffy. 



M54 and M55. These also were two white, woolly colonies. 



M56 (origin, PI. XXX) and M60. These were from a dark fast- 

 growing sector of M26 and maintained character. 



