4 
Casey A. Wood. 
during embryonic life., but as soon as the birdlet is hatched the 
eves are closed and remain closed for several davs. There is no 
evidence that any organic union occurs between the lid margins in 
these “born-blind” birds. In all probability the closed eyes are due 
to tonic contraction of the orbicularis as a light reflex act. 
The muscles of the eyelids are the orbicularis palpebrarum , the 
levator palpebrae superions , and the depressor palpebrae infer ioris. 
According to Leuckart ( Graefe-Saemisch Handbuch d. ges. Augen- 
heilhunde, Yol. II, 1876, p. 145) and Doenecke, they are all striated 
muscles. However, Zietzschmann ( Ellenberger s Ilandbuch der 
vergl. mih. Anatomie, I, p. 535) believes the orbicularis to be a 
smooth muscle. The depressor of the lower lid is much stronger 
(as one might expect from the fact that the latter is more mobile 
than the upper) and better developed than the levator of the upper 
lid. It is certainly attached to the lower margin of the tarsus, but 
it (probably) also spreads over the anterior surface of the lid plate 
and is attached there. According to Zietzschmann both muscles 
are joined at their origin in the depths of the orbit, where they 
form part of a common muscle mass; although Slonaker has not 
been able to verify this finding. Slonaker, however, agrees with 
Zietzschmann that the orbicularis is a smooth muscle, while both 
the depressor and levator palpebral are striated. 
In experimenting with the Sparrow the writer found that the 
third lid is the only one that closes when an object is “poked” at 
the bird’s eye. The paired lids close very slowly, if at all, under 
the stimulants used. The physiological experiments bear out what 
was found anatomically, viz., that the orbicularis is controlled by 
the sympathetic. 
The orbicularis is an extremely thin muscle in the Sparrow, as 
may be seen by examining the accompanying figure. It appears as 
mere lines on horizontal section, and as small dots in vertical sec- 
tions. It is attached to the skin and does not, as in Man, spread 
out and mingle its fibres with neighboring forehead, tarsus (of the 
lower lid) and lachrymal apparatus muscles. 
There is not, so far as the writer could discover, any analogue in 
the Bird's lid of the human muscle of Biolan. 
Although there is every reason to believe that the non-striated or- 
bicularis of Passer domesticus is supplied by fibres deriver from 
the sympathetic, yet the extremely difficult histological problem of 
establishing this fact, by demonstrating the course of the fibres 
and determining their origin, has not yet been solved. 
In the ITen the ciliary feathers , or eyelashes, more nearly re- 
