IV 



II. Evidence and discussion of the occurrence of saltation within the genus Helmin- 



thosporium : PAGE 



Introductory 139 



Characters of saltants as shown in transfers 141 



Tendencies in saltation 145 



Stability of the saltants 145 



Stability of the saltants through the conidia 146 



Apparent reversions 147 



Supposititious causes of the variant sectors 147 



Saltations from single conidia 149 



Frequency of saltation 150 



Saltations occurred on various media 152 



Saltations and modifications occurring in test-tube cultures . . . . . . 152 



Saltations in nature . 154 



Notes concerning selected individual saltants 155 



General discussion of saltation 157 



Taxonomy 164 



Conclusion ^ 168 



Summary 168 



Literature cited 171 



Appendix: 



Methods 179 



List of Helminthosporiums used for purposes of comparison 181 



Discussion of foregoing list with several brief descriptions 184 



Graphs: Figures A Y. 



Plates: VII XXXIV. 



