INTRODUCTION 63 
examples of it are comparatively scarce. Moreover, he stated subsequently 
that he thereby hoped to excite other naturalists to share with him the 
investigations he was making on a subject which had hitherto escaped 
notice or had been wholly neglected, since he considered that he had 
proved the disposition of the feathered tracts in the plumage of Birds to 
be the means of furnishing characters for the discrimination of the various 
natural groups as significant and important as they were new and un- 
expected.1. There was no need for us here to quote this essay in its 
chronological place, since it dealt only with the generalities of the subject, 
and did not enter upon any systematic details. These the author reserved 
for a second treatise which he was destined never to complete. He kept 
on diligently collecting materials, and as he did so was constrained to 
modify some of the statements he had published. He consequently fell 
into a state of doubt, and before he could make up his mind on some 
questions which he deemed important he was overtaken by death.2 Then 
his papers were handed over to his friend and successor, Burmeister, 
afterwards and for many years of Buenos Aires, who, with much skill 
elaborated from them the excellent work known as Nitzsch’s Pterylographie, 
which was published at Halle in 1840. ‘There can be no doubt that the 
editor’s duty was discharged with the most conscientious scrupulosity ; 
but, from what has been just said, it is certain that there were important 
points on which Nitzsch was as yet undecided—some of them perhaps of 
which no trace appeared in his manuscripts, and therefore as in every 
ease of works posthumously published, unless (as rarely happens) they 
have received their author’s “imprimatur,” they cannot be implicitly 
trusted as the expression of his final views. It would consequently be 
unsafe to ascribe positively all that appears in this volume to the result of 
Nitzsch’s mature consideration. Moreover, as Burmeister states in his 
preface, Nitzsch by no means regarded the natural sequence of groups 
1 Ti is still a prevalent belief that feathers grow almost uniformly over the whole 
surface of a Bird’s body ; some indeed are longer and some are shorter, but that is 
about all the difference perceptible to most people. It is the easiest thing for any- 
body to satisfy himself that this, except in a few cases, is altogether an erroneous 
supposition (see PrERYLOSIS). Before Nitzsch’s time the only men who seem to have 
noticed this fact were the great John Hunter and the accurate Macartney. But the 
observations of the former on the subject were not given to the world until 1836, 
when Owen introduced them into his Catalogue of the Museum of the College of 
Surgeons in London (vol. iii. pt. ii. p. 311), and therein is no indication of the fact 
having a taxonomical bearing. The same may be said of Macartney’s remarks, which, 
though subsequent in point of time, were published earlier, namely, in 1819 (Rees’s 
Cyclopedia, xiv. art. ‘Feathers’). Ignorance of this simple fact has led astray 
many celebrated painters, among them Landseer, whose pictures of Birds nearly always 
shew an unnatural representation of the plumage that at once betrays itself to the 
trained eye, though of course it is not perceived by spectators generally, who regard 
only the correctness of attitude and force of expression, which in that artist’s work 
commonly leave little to be desired. Every draughtsman of Birds to be successful 
should study as did Mr. Wolf, the plan on which their feathers are disposed. 
2 Though not relating exactly to our present theme, it would be improper to 
dismiss Nitzsch’s name without reference to his extraordinary labours in investigating 
the insect and other external parasites of Birds, a subject which as regards British 
species was subsequently elaborated by Denny in his Monographia Anoplurorum 
Britannizx (1842) and in his list of the specimens of British Anoplwra in the collection 
of the British Museum. 
