87 [ Vol, xl. 
successful naturalist adds during his life something to the 
accumulated mass of accepted facts upon which others shall 
build up either additional facts, or shall make some discovery 
which shall further enlighten humanity upon the ways and 
means of the great mystery of creation and perpetuation of 
life by evolution. 
To me it seems that when we find out a few facts entitling 
geographical races to trinomials, we are adding a few bricks 
to the foundation of the building whose coping-stone shall 
be complete knowledge. 
Dr. Ernst Harter said he, needless to say, agreed with 
almost every word Mr. Stuart Baker said, but he objected 
to make supposed intergradation between two forms a 
criterion of the subspecies. Though we are convinced that 
intergradation between subspecies must have existed, and 
exists now in many cases, there were, nevertheless, numerous 
instances in which no intergradation could be traced—in 
fact, we seldom found it to exist. This was the case 
with many forms replacing each other on continents, but 
still more often, of course, with island forms. American 
ornithologists for a long time regarded the existence of 
intergradation necessary for a supposed subspecies, in conse- 
quence of which they treated island forms, which were the 
most typical examples of subspecies, as species; but they 
had now recognized the fallacy of their treatment and 
looked upon representative island forms as subspecies. 
The question having been raised, how a subspecies should 
be defined, he wished to repeat what he had often said 
elsewhere, that he regarded as subspecies forms which 
agreed in their main characters while they differed in 
details (either of colour, markings, or dimensions), and repre- 
sented each other geographically—or that subspecific characters 
were “differences combined with geographical separation,” 
agreement in structure and general features, of course, being 
established. 
With regard to different habits these need not always 
be peculiarities of distinct subspecies, but often were due to 
a5 
