570 TRANSACTIONS OF SECTION K. 
from preconceptions based upon limited paleontological data, but from an inten- 
sive study of the living plants themselves. To widen as far as possible the 
criteria of comparison, by making, for instance, every possible use of cellular, 
physiologico-chemical, and especially secretory detail, and of minor formal 
features, such as the dermal appendages, or by initiating a new developmental 
morphology of the flower from the point of view of its function as a whole: and 
with its physiological end clearly in sight, viz., the maturing, nourishing, and 
placing of new germs. To make on some such basis intra-ordinal, and intra- 
generic comparisons with a view to the phyletic seriation of closely related forms ; 
and so to construct probable short series, which may subsequently be associated 
into larger phyletic groupings. This should be checked wherever possible by 
physiological probability. A keen eye should be kept upon such information as 
geographical distribution and paleontology may afford, and especially upon the 
fossils of the Mesozoic Period. What is above all needed for success among the 
Angiosperms is new criteria of comparison, to meet the far-reaching difficulties 
that follow from parallel development and recent adaptation. If some such 
methods be adopted, and strenuously pressed forward, the task should not appear 
hopeless, though it cannot be anything else than an arduous one. 
I cannot conclude without some remark on the bearing of parallel or conver- 
gent development, so fully exemplified in the Filicales, upon the question of the 
genesis of new forms. Anyone who examines, from the point of view suggested 
in this Address, the larger and well-represented divisions of the Vegetable King- 
dom must be impressed with the extraordinary dead level of type to which their 
representatives have attained. In most of these divisions the phyletic history is 
obscured, partly by the absence of any consecutive paleontological record, but 
chiefly by the want of recognised criteria for their comparison. This is very 
prominently the case for the Mosses, and the Angiosperms. 
But it may be doubted whether these large groups differ in any essential point, 
in respect of the genesis of their multitudinous similar forms, from the Filicales, 
in which the lines of descent are becoming clearer through additional knowledge. 
Suppose that we knew of no fossil Ferns; and that none of the early Fern-types 
included under the term ‘Simplices’ had survived in our living Flora: and that 
the Filicales of our study consisted only of the 2,500 living species of the old 
undivided genera of Polypodium, Asplenium, Aspidium, and Acrostichum. Then 
the phyletic problem of the Filicales would appear as obscure as does that of the 
Mosses, or of the Angiosperms of the present day. 'They would present, as these 
great groups now do, an apparent dead level of sameness in type, though the 
phyletic starting-points in each may have been several and distinct. There is 
every reason to suppose that in the phylesis of the Mosses or the Angiosperms also 
there has been a parallel, and even a convergent, development of the same nature 
as that which can be cogently traced in the Filicales: but that it is obscured by 
the obliteration of the early stages. Internal evidence from their comparative 
study fully justifies this conclusion. How, then, are we to regard this insistent 
problem of parallelism and convergence from the point of view of genetic study? 
A belief in the ‘inheritance of acquired characters,’ or, as it is sometimes 
expressed, ‘ somatic inheritance,’ is at present out of fashion in some quarters. 
But though powerful voices may seem to have forced it for the moment into the 
background, I would take leave to point out that such inheritance has not been 
disproved. All that has been done, so far as I understand the position, is to show 
that the evidence hitherto advanced in support of it is insufficient for a positive 
demonstration. That is a very different thing from proving the negative. We 
hear of ‘Fluctuating Variations’ as distinct from ‘Mutations’; and it is 
asserted that the former are somatic, and are not inherited, while the latter are 
inherited. This may be held as a useful terminological distinction, in so far as 
it accentuates a difference in the heritable quality. But it leaves the question of 
the origin of these heritable ‘Mutations’ quite open. At the present moment I 
believe that actual knowledge on this point is very like a complete blank. Fur- 
ther, it leaves indefinite the relative extent and proportion of the ‘ Mutations.’ 
It is commonly held that mutations are considerable deviations from type. I 
am not aware that there is any sufficient ground for such a view. It may 
probably have originated from the fact that the largest are most readily observed 
and recognised as reappearing in the offspring. But this is no justification for 
ignoring the possibility of all grades of size or importance of heritable deviations 
from type. 
