174 SECTIONAL ADDRESSES. 
can continue to call ‘ pure races’ by that name or any more modern 
equivalent, and ‘elementary species ’ may still be called so, or I have 
no objection to calling them ‘Jordanons.’ In the interests of practical 
taxonomy they necessarily have to be kept subordinated to Linnean 
species. There are difficulties enough either way, but they are, as it 
seems, less if we adopt the conservative course. That many Linnean 
species are real units of a definite order is generally admitted. Dr. 
Lotsy himself dwells on their distinctness, which depends on their 
usually not inter-crossing, and appears to be shown by the fact that 
among animals members of the same species recognise each other as 
such and habitually breed together. Such habitual breeding together 
under natural conditions is perhaps the best test of a species in the 
Linnean sense. ‘The units within each Linneon (=species) form an 
inter-crossing community.’ (Lotsy.) He adds: ‘Consequently it is 
Nature itself which groups the individuals to Linneons.’ These ‘ pair- 
ing communities’ have recently been re-christened by Dr. Lotsy 
‘ syngameons,’ ? a good name to express this aspect of the old ‘ species.’ 
I do not propose in these brief remarks to venture on that well-worn 
subject the inheritance of acquired characters—i.e. of such characters 
as are gained during the lifetime of the individual by reaction to the 
environment. There has always been a strong cross-current of opinion 
in favour of this belief, especially, in our own time, in the form of 
‘unconscious memory,’ so ably advocated by Samuel Butler and sup- 
ported by Sir Francis Darwin in his Presidential Address to the British 
Association at Dublin. Professor Henslow, as we all know, is a 
veteran champion of the origin of plant structures by self-adaptation 
to the environment. On the other hand, some geneticists roundly deny 
that any inheritance of somatically acquired characters can take place. 
In any case, the evidence, as it seems, is still too doubtful and inadequate 
to warrant any conclusion, so, however fascinating such speculations 
may be, I pass on. 
To bring these introductory remarks to a close, we see that while 
the theory of Descent or Evolution is undisputed, we really know 
nothing certain as to the way in which new forms have arisen from 
old. During the reign of Darwinism we commonly assumed that this 
-had happened by the continual selection of small variations, and we 
are no longer in a position to make any such assumption. 
We have been told on high authority that ‘as long as we do not 
know how Primula obconica produced its abundant new forms it is no 
time to discuss the origin of the Mollusca or of Dicotyledons.’ (Bate- 
son.) Yet this is just the kind of speculation in which a paleontologist 
is apt to indulge, and if kept off it he would feel that his occupation 
was gone! However, so long as we may believe, as already said, that, 
on the whole, like breeds like, that grapes do not spring from thorns 
or figs from thistles, there is perhaps still sufficient basis for some 
attempt to interpret the past history of plants in terms of descent. 
But certainly we have learnt greater caution, and we must be careful 
*Lotsy, La Quintessence de la Théorie du Croisement. Archives 
Néerlandaises des Sciences, Sér. III. B., t. iii., 1917. 
