129 
of the tensor chorioideae present an alternation in their strongest 
development. Bricke’s muscle and Mürrer's muscle in turn disappear 
completely. When Brücke’s muscle loses ground Crampron’s muscle 
avuils itself of the free space on the sclera to fasten its fibers more 
back wards. 
When summarizing the above we see that in the pigeon’s eye 
there exists near the eyesplit in the nasal-inferior quadrant a muscular 
fascicle, situated medially to the plexus ciliarus, running from the 
sclera to the inner lamella-medial part of the cornea. This origin 
and insertion exclude the muscle from the known types of ciliary 
muscles of the bird’s eye. At that spot Crampron’s muscle is strongly 
developed, Brücke’s muscle is only slightly developed, while MiLier’s 
muscle has completely disappeared. 
In the preparation of the uvea the absence of this muscle accounts 
as well for the absence of the pigment as for the absence of the 
bridging by the basement membrane. 
The innervation also is furnished by the plexus ciliaris. D. TRETJAKOEF 
(1906) describes the M. protractor lentis in the salamander’s eye. 
This muscle, like our muscular fascicle lies near the eyesplit in the 
inferior half of the corpus ciliare. This muse. protactor lentis is not 
related to the M. tensor chorioideae. TreTsakorr’s’) muscle extends 
downward from its origin and bends temporally towards the corneo 
scleral border. 
The difference from the discussed muscular fascicle in the pigeon’s 
eye, lies in the fact that contrary to the M. protr. lentis this fascicle 
extends upwards to bend round temporally afterwards, anyhow as 
far as those of its fibers are concerned that are nearest to the 
horizontal plane; also in this that some fibers act like the tensor 
chorioideae. For the rest there are many points of similarity. Among 
the eye-split-rests in the deep-sea fishes also a muscle, the M. retractor 
lentis may be discerned. 
This muscular fascicle does not occur in the fowl. NussBauM (1897 *) 
does not mention this pecularity in the corpus ciliare for the simp Je 
reason that he describes the eyesplit in the fowl. 
Method of fixation and treatment was as follows. Fixation by 
means of perfusion of the bloodvessels of the head upwards from 
the truncus arteriosus cordis and subsequently through submersion 
into the fixative employed. The fixatives were of low concentration 
1) D. Trersakorr 1906 „Der Musc. protract. lentis im Urodelenauge’’. Anatom. 
Anzeiger. B. 28. 
#) M. NussBpaum 1897 „Die pars ciliaris des Vogelauges. B. 57, p. 346. 
9 
Proceedings Royal Acad. Amsterdam. Vol. XXIV. 
