238 proceedings: biological society 



while a species does not. Two kinds of intergradation must be dis- 

 tinguished, that due to fluctuating variation, which indicates sub- 

 specific rank, and that due to hybridism, which may occur between 

 species. As most systematic work is done with herbarium specimens, 

 it is not possible to distinguish these by breeding tests, and their dis- 

 crimination is a matter of judgment and experience. Furthermore, 

 the absence of intergradation is not in itself a criterion of specific rank. 

 Many unit-character forms, very distinct in appearance, such as al- 

 binos or forms with peculiar leaves, will not be found to intergrade, 

 and they even have rather distinct geographical ranges. In such 

 cases the rank to be given the form in question depends on the extent 

 of the botanist's field experience. In general, forms distinguished 

 by several constant characters are species; forms distinguished by only 

 one or by inconstant characters, subspecies ; but there is no absolute 

 test which can be applied, and in doubtful cases the decision depends 

 on the experience and point of view of the botanist. 



Each of the above speakers was limited to ten minutes for the pre- 

 sentation of his remarks. After the formal remarks a general dis- 

 cussion ensued in which Messrs. A. S. Hitchcock, A. N. Caudell^ 

 P. Bartsch, N. Hollister, S. A. Rohwer, Iv. O. Howard, V. Bailey, 

 and M. W. Lyon, Jr., took part. 



M. W. Lyon, Jr., Recording Secretary. 



