The Biology of Polyporus Pargamenus Fries 5a 
occurring in the eastern and western United States. In view 
of the great array of intergrading varieties of this poroid 
form, the exact status of this form was doubtful in the mind 
of the writer.'" Accordingly a number of specimens of the 
above-mentioned forms were submitted to Mr. C. G. Lloyd, 
who regards them all as forms of the one species. In Mr. 
Lloyd’s opinion there is nothing in the more obvious varia- 
tions of the plant nor in the microscopic structure to justify 
trying to maintain different species where there are so many 
connecting forms. 
Just whether the extremely variable poroid form of 
Polyporus pargamenus is an ecological adaptation, a racial 
form, or a distinct species, the writer would not like to state 
in the complete absence of any cross inoculation data. At 
any rate, among the hundreds of specimens examined by 
him during the. course of this study, few intergradations 
occur between the poroid form on species of Populus and 
Salix, and the typical hydnoid form on the woods of these 
and other genera. In his opinion the ultimate criterion for 
making the poroid form a distinct species would be afforded 
only by the making of cross inoculations. Pure cultures of 
the poroid form on species of Populus and Salix should be 
obtained and inoculated on other species of dicotyledonous 
woods. At the same time the typical hydnoid form of Poly- 
porus pargamenus occurring on these and other species of 
trees should be inoculated on species of Populus and Salix 
and the resulting sporophores compared. The results 
obtained should show whether this poroid form is a distinct 
species that may be inoculated and reisolated from various 
species of trees other than species of Populus and Salix, or 
whether it is a biological form aberrant from the type of 
Polyporus pargamenus and arising as a result of some 
peculiarity of the wood of the species of these two genera 
that serve as hosts. Furthermore, such an experiment, when 
conducted under controlled conditions, should determine the 
“In some of the herbaria examined many of the specimens classified 
under Polyporus (Coriolus) subchartaceus are merely imperfectly 
developed or old weathered specimens of Polyporus hirsutus on Populus. 
