143 



Variations in septation were also noted; thus in Fig. R, Graphs 79-82 

 are quite different from Graphs 83 and 84, while all of these are lower than 

 the results gotten from H. No. 1 in Graph 35, Fig. J. I attach but little 

 value, however, to these variations because they seem inconstant. 



Variation in conidial shape is common, some saltants showing the 

 sides more nearly parallel than others, and the conidium as a whole less 

 elliptical or fusiform. 



Variation in submerged mycelium. Aside from rate of growth and 

 variation in branching which resulted in changes in density of the colony, 

 differences in the submerged mycelium were observable in but two cases, 

 most strikingly so in M26. In this saltant certain hyphal threads near 

 the edge of the colony appeared to be much more vigorous than their 

 neighbors, becoming a trifle thicker, and lengthening with such rapidity 

 as far to outstrip the others, reaching out as single strands to a consider- 

 able distance beyond the usually even frontier of the colony, beginning 

 then a dense, bushy branching in all directions, reminding one of witches'- 

 brooms in trees. Numerous outposts of this kind give a peculiar lumpy 

 appearance to the colony as seen by the naked eye. This peculiar mode 

 of branching was clearly to be seen in M26, where it originated, and was 

 frequent throughout subsequent transfers. Instead of single threads 

 reaching out in this way, the mycelium sometimes formed fascicles which 

 would grow out rapidly into new territory without branching, then sud- 

 denly branch profusely, forming a dense brush. These two rare characters 

 were striking in effect both to the naked eye and under the microscope. 

 Nearly every transfer from M26 or its descendants gave colonies with 

 very strikingly marked sectors, characterized essentially by abundant 

 conidial production, and therefore dark in color. The other sectors bore 

 few conidia, were pale, and being a trifle less rapid in growth they were 

 usually crowded out (PI. XXX, lower fig.). These characters were main- 

 tained through many transfers. (See PI. XXXI.) 



Variation in aerial mycelium. Saltant sectors and their progeny 

 often differed from the originals in the abundance and character of the 

 aerial mycelium. In some cases it was so scant as to be unnoticeable; 

 in other cases so abundant and floccose as to obscure from vision the 

 colony beneath. In character it varied from loose and fluffy to "ropy," 

 the latter term indicating a tendency of many mycelial strands to twine 

 together (Fig. 5, c, p. 104) . In other cases it collected in clumps, the process 

 being attended by peculiar distortions (Fig. 6, e) . In some saltants these 

 clumps were abundant and aggregated; in others few and scattered (PI. 



