EE —— 
RECENT PROGRESS OF SYSTEMATIC BOTANY. AS 
description or detailed indications of its affinities, &c. However carefully 
the diagnosis may be worded so as to distinguish the species from those 
previously published, it would be insufficient for its identification, and full 
descriptions would be inadmissible from the plan of the work. At the same 
time it is to be expected that the author, in preparing the ‘ Synopsis,’ should 
meet with new forms, which he may be desirous to make known, in order 
to render his work as complete as possible. But his course should be to give 
their full history in a separate monograph, to which, when published, he 
could refer in the ‘Synopsis.’ He should here not only thus avoid all addition 
to the numerous puzzles with which the science is overloaded from insuffi- 
cient description, but strictly abstain from all mention of manuscript and 
other names which, accerding to the recognized rules of nomenclature, are 
not admitted as sufficiently published. 
The grade of plant-race to which the specific name and diagnosis should 
be attached, would be the species in the Linnean sense, which, though not 
susceptible of a strict definition, is pretty generally understood amongst 
botanists, whether they may designate it as a true species, a Linnean, or a 
compound species. The ‘Synopsis’ might also distinguish marked varieties 
whose admission or rejection as species might be doubtful; but the innume- 
rable forms variously termed varieties, subspecies, or critical species should 
be passed over in silence, as their admission would simply render a general 
work impossible, and a more partial one comparatively useless. The enume- 
ration and distinction of the various forms of Brassica campestris and oleracea, 
of Pisum sativum, Viola tricolor, &c. may be serviceable to the agriculturist 
or gardener, that of the forms of Rubus fruticosus may be interesting to 
the investigator of the flora of a limited district, but they are only useless 
encumbrances to the general systematist as well as to the naturalist in other 
branches who would have to make use of the ‘ Synopsis; ’ and the names and 
diagnoses of two hundred forms of Draba verna would be a simple nuisance, 
of no use whatever to any one*. 
Taking the species, therefore, in the Linnean sense, we should, with Alph. de 
Candolle, estimate the number of Phenogams now published, or in the course 
* The mode of dealing with species which in the present state of vegetation pass into 
each other through a series of intermediate forms which cannot fairly be supposed to be 
hybrids, is well discussed by Nageli in a series of papers in the ‘Sitzungsberichte’ of the 
Munich Academy for 1866, the result of careful observation chiefly of the genus Hiera- 
cium. After admitting himself to have been originally a firm believer in the fixity of 
species and a strong advocate of the hybrid parentage of the large number of intermediate 
forms observed, he acknowledges his conversion to the doctrine of evolution. ‘In the 
present state of the science” he sees “no other possibility than the assumption that the 
species of Hieracium have arisen by transmutation either from extinct or from still sur- 
viving forms, and that there are still persistent a great number of the intermediate stages 
(xaces) formed either by the original differentiation of the extinct species, or in the course 
of the transformation of one yet living species into the diverging forms.”—Sitzungsber. 
1866, i. 330. 
In a subsequent paper he shows that the genus Hieraciwm affords instances of great 
diversity in the degree to which differentiation has attained and in the definiteness of the 
species established by the extinction of intermediates. He instances, amongst those to 
which he would in their present state assign the rank of species :— 
1. Aggregate forms, such as H. p2losella, which cannot as yet be separated into distinct 
groups. H. Hoppeanum, Schult., H. Pelleterianum, Mérat, H. pseudopilosella, Jen., are 
not yet sufficiently isolated by the disappearance of intermediate forms to be ranked as 
species. 
PO. Forms which, by the disappearance of closely allied ones, have attained sharper and 
more fixed jimits, and yet between which isolated intermediates may still be found, are 
exemplified by H. awricula, H. aurantiacum, and H. pilosella, or by H. murorum, H. vil- 
losum, and A. glaucum. On the other hand, it is wacertain whether the relations of 
