304 ON THE EUKOPEAN SPECIES OF FESTUCA. 



grades of value. Therefore we shall much ofteuer meet with 

 specimens which cannot be placed with any known variety of a 

 species than with specimens which cannot easily be placed with a 

 distinctly marked species. And, between species, such inter- 

 mediate forms hardly can occur, otherwise they would cease to be 

 species. 



Prof. Hackel says he has sometimes described as species fonns 

 with which no connecting links to neighbouring forms were known 

 to him, but he has done this only when he has been led, fi'om 

 other considerations, to believe such links to be really existing, or 

 in cases in which there existed but one distinguishing character. 

 In the latter case the separation of the form from nearly allied 

 ones is evident, for if a form from the birth of a differential 

 character has separated from the rest, then such a form continues 

 to vary for some time in different directions. The deviation 

 continues to work till it builds, in addition to the first, again 

 secondary differential characters, and these strengthen, if we 

 sujDpose a sufticiently long time to elapse, until the form become a 

 well marked species. 



The presence of a sinfjle distinctive character, on the other 

 hand, betokens that we have before us the commencement of the 

 development of a species, and examples usually present themselves, 

 sooner or later, which will show the distinguishing character less 

 sharply defined. 



The author names ^^ varieties'' those forms which in their most 

 marked representatives are well characterised and distinguishable, 

 are numerous, but of which examples not unfrequently occur which 

 cannot be accurately defined, and which must be looked upon as 

 connecting links to other forms. As a rule, he states that he has 

 always pointed out the afiinity which he has perceived each variety 

 to possess to any other form, since he believes this to be very 

 important as a means for determining its origin. 



As ^' sub varieties" the author has distinguished those forms 

 which are separated from one another mostly by one single 

 character, unstable or of low value ; should a second and about 

 equally unstable character be present, then the form would be 

 intermediate between variety and subvariety, and the author has 

 sometimes pointed out instances. There are plenty of forms to 

 which one may rightly assign a higher or a lower rank, on account 

 of their occupying an intermediate position between the two. The 

 relationship of subspecies one to another, or to a frequently occm-ring 

 variety, is in most cases evident. It is at least possible to name 

 the form from which the subvariety may be supposed to have 

 originated, and in many cases in which the subvariety occurs 

 sparsely within a circumscribed area there can be no doubt 

 respecting its origin ; as an example, the author gives — subvar. 

 a u rata of F. rubra, subsp. viulacea, which has sprung fi'om F. 

 rubra''' var. yeinina. 



As a help to weigh the value or dignity of a form, the author 



• In the text we read •' subvar. gemina," which must evidently be a misprint. 



