14 
nigra, Oe. fiisca, Fuligula marila, Glaiicion clangiila, Somateria 
mollissima, Pagonetta glacialis), gulis and terns, owls, f Oliis 
brachgotiis, O. niilgaris, Bubo maciilosiis), birds of prey (Astiir 
paliimbariiis, A. nisiis, Buleo vulgaris, Cii'cus cyaueus, C ærugi- 
nosus, Sarcorhamphus gryphus), waders f Numenius arcuatiis, 
Grus antigone, Fulica aira), parrots (Loriculus galgulus), wood 
peckers (Piens marlius), passerine birds fSturnus vulgaris, Alaiicla 
arvensis). 
In the literature I could not find anything concerning this mat- 
terA) It was my intention, therefore, to pursue the examination 
and to publish my results, but other work came in the way. Only 
occasionally, in my leetures and during my courses, I have men- 
tioned my observation of these facts, which still for many years 
were to escape attention. At last Chappellier 1910 published his 
remarks about Wolffian duets found in adult females of some fin- 
ches (sparrow, canary, serin (Seriniis horlulauus), and hybrid be- 
tween goldfinch and canary, 1. c. 1910, p. 59). Also Chappellier 
was unable to find anything regarding this matter in the litera- 
9 In the older literature, in works by Rathke and Jacobsen, I have 
found some indications pointing in the right direction. Rathke (1825, 
§ 68, p. 25) says regarding the structure now recognised as the mesone- 
phric (or Wolffian) duet, in the chicken: “Beim weiblichen Geschlechte 
hat der beschriebene Theil seine grosste Ausbildung in den vorletzten 
Tagen der Bebriitung erreicht. Dann aber verkummert er, gleich den 
Wolffsehen Korpern, immer mehr, stirbt ab, und verschwindet zuletzt 
geraume, aber unbestimmte Zeit nach dem Auskriechen 
des Huhnchens ganzlich.” On Tab. III, Fig. 12, he represents very 
plainly the anterior part of the duets (together with the right atrophying 
mesonephros) of a hen-chicken, three weeks after hatching. jacobson 
in the work, where he is giving his interpretation of the “Gartnerian 
tubes” as remnants of the mesonephros, says in a note (1832. p. 179): 
“Ogsaa hos Fuglene bliver Primordialnyrernes Udførselsgang, i det mind¬ 
ste en Tid lang, som Rudiment tilbage.“ (“Also in the birds does the ex- 
cretory duet of the primordial kidneys persist as a rudiment, at least for 
a long time”.) I have not in J.’s different works found mentioned any 
observations, on which this note may direetly be founded, and therefore 
I am not able to settie if J. himself may actually have made such ob¬ 
servations — f. inst. during his investigation of the venous system of 
the kidney in birds — or if he in using Rathke’s work from 1825, which 
he knew and quotes, has interpreted the facts, set forth there, with the 
same perspicacity which led him to the correct explanation of Gart- 
ner’s “glandular organ” of ruminants and swine. 
