400 BOTANICAL GAZETTE [june 



adapted to it. This sudden occurrence of new forms is a vexing 

 question. It may be due to the naturalization of some exotic form, 

 but this does not seem to be satisfactory. The best explanation, at 

 least with variable forms, seems to be the production of new strains 

 or forms from the old ones. 



What needs to be done now, and what must be done before we 

 can formulate any idea as to the limits of species among these forms, 

 is to grow them on different hosts and different media for long periods, 

 to see if they will adapt themselves to the new hosts and media and 

 will become fixed. It seems probable frcm this study that such 

 varieties could be built up, and perhaps sooner than we would 

 expect. 



NOMENCLATURE 



Some doubt has been expressed lately as to the validity of the genus 



Glomerclla. 



forms 



put in some of the closely allied genera. There are three other genera 

 which are quite similar, all of which doubtless have had described 

 under them, at one time or another, forms that belong properly to 

 Glomerella. These are Physalospora, Guignardia, and Phomato- 

 spora. None of these genera are understood very well by mycolo- 

 gists, and a thorough monograph is needed before w^e shall be sure of 

 our ground. But there are some characters which seem to prevent 

 the forms of Glomerella from being placed in the other genera. A 

 btroma may be present in the forms of Glomerclla, w^hile it is entirely 

 lacking in the others. Odier distinguishing charact'^rs are the more 

 or less well-developed neck of the perithccium and the lack of 

 definite paraphyses. 



The genus Glomerella is extremely variable, and there remains 

 little doubt that some of the individuals would answer very well to 

 the descriptions of the other genera; but it seems that the forms 

 taken as a whole are distinct enough for a separate genus; at least this 

 is the position I should take for the present. M aubl \nc anrl L asnier 

 (27) have recently described a perfect stage of a Gloeosporium on an 

 orchid as a Physalospora. Although their material has not been seen, 

 it seems probable that they had but a form of Glomerella. They de- 

 scribed their specimen as possessiner naranhvses. hut their drawings 



y 



