540 ON THE SPECIFIC CHARACTERS OF BIRDS. 
varies from deep chocolate to nearly white, the feathers are 
the same in form and arrangement, whatever they may be 
in regard to surface. 
Although I have not, by any means, exhausted the sub- 
ject, while in truth I may, on the other hand^ have ex- 
pressed myself too diffusely, perhaps too vaguely, on some 
points, I cannot, in prudence, continue to impose upon you 
the irksome task of listening longer to a subject that has 
already been fully announced. It is a subject that would 
seem worthy of some attention ; unfortunately, however, it 
requires minute, patient, strict investigation. But surely 
Nature cannot be too closely interrogated, nor can the la- 
bour of examining the plumage of birds be misapplied by 
the ornithologist. It is to Nature herself that I make my 
appeal, for the correctness of my ideas. The question is 
not, Are the views which I have taken such as may readily 
be entered into by others ; but are they such as will be 
found, on examination, to lead to important results, while 
they are, at the same time, founded on Nature only ? To 
determine this question, is a task that, in all probability, 
very few, or none, will readily trouble themselves with. I 
shall not, however, for this be the less induced to cultivate 
the subject ; and if the result of my investigations prove of 
such a nature as I anticipate, I may have the satisfaction 
of again soliciting the attention of the Society, to a com- 
munication more worthy of their notice than the present. 
Edinburgh, 
mh February 1823. 
