276 Mr Bernard , On the Unit of Classification 
happen to discover. Time and further work will show us the 
completed chains and reveal to us where forms are diverging, 
where special structures having apparently reached a climax 
beyond which they cannot go remain stationary until they die 
down. And these completed chains will show us how the forms 
can be genetically grouped and for the first time tell us what a 
‘ species ’ really is. 
The difficulty which we have just been considering, arising 
from the existence of shades of variation so fine that the units 
I am advocating will be in comparison as coarse and clumsy as 
the present Linnean types of species, naturally leads us to notice 
a method of dealing with fine variations which is daily becoming 
more popular. I refer to the mathematical treatment of fine 
variations in the sizes of definite selected structures. This 
method of work is so far removed from the present rough and 
ready use of hypothetical genetic groups as units with which to 
start our classification that we are not surprised to hear Professor 
Davenport declare, from its standpoint, that the Linnean system 
of naming is doomed 1 . The mass of systematists simply stand 
aghast ; that the work is excellent few, I suppose, doubt, but 
where can it be made to hinge on with the present work ? It 
seems almost to belong to another sphere. I think, however, 
after what has been said, that we can easily see where this work 
will fall into its place. It also takes the ‘ form ’ for its unit ; every 
single specimen, indeed, no matter how slightly it differ from its 
neighbours, counts as one of equal value for the work as any other. 
But the method belongs to a different department of research 
from the system of sorting forms for the purposes of arranging 
them into series which I am advocating. It is in reality a 
collateral study, which may or may not be helpful to classification. 
The arrangement of the varying forms of life as so many distinct 
units into evolutionary series is the objective of the systematist 
of the future. I do not see how this will need the aid of mathe- 
matical formulae. It seems to me only to require careful com- 
parisons of structure, that is, of the relative dispositions and 
forms of the component parts, rather than of mere quantitative 
differences in parts otherwise similar. The mathematician, as 
far as I can see, has no part nor lot in the matter, it belongs 
solely to the comparative anatomist or morphologist 2 . But as 
soon as the new unit of classification has been adopted, then the 
1 See Nature, Oct. 5, 1901. 
2 I have already endeavoured to give samples of analyses of structure with 
the object of elucidating lines of evolution. They are not, alas, models but poor 
samples; e.g. in my ‘ Apodidae ’ (Nature Series, 1892), but more philosophically 
in the Comparative Morphology of the Galeodidae (Trans. Linnean Society, vi. 
1896), and I have a third work on the Evolution of the Coral Skeleton which is in 
course of preparation. 
