34 



THE FUNDUS OCULI OF BIRDS 



a 1% mixture of curare put into left eye of 

 three adult English Sparrows, two <?, one 9, 

 at 11 a.m. Thursday, March 28, 1912. 

 Result negative at twelve o'clock. 



April 1, 1912. Put one drop of }/2% nico- 

 tin into the left eye of two Sparrows, adults, 

 one 9, one <?, at 9:35 A. M. Pupils in each 

 case — half light — were 2 mm. in diameter 

 before the instillation. 10:15 A. M., no effect 

 as to dilation or reflex to light in 0% so then 

 put in one drop of 1% nicotin. Bird became 

 slightly "groggy" in 4 minutes. 10:20 A. M. 

 9, left pupil barely dilated more than right, 

 instilled 1 drop 1% solution nicotin: no gen- 

 eral effect in 5 min. 10:25, ditto &. 11:30, 

 very slight, if any difference in pupils. 2:25 

 p. m., same day, put a drop of 2% into left 

 eye of same 9 and d" sparrows. They both 

 became quite "groggy" in one minute but 

 recovered in five minutes so as to sit up and 

 fly easily about the cage. At 2 :40 p. m. no 

 change in pupil. 3:10 p. M., both birds quite 

 lively and both left pupils dilated to 3 mm. 

 At 4:30 tf's pupil dilated; 9 normal. Both 

 birds normal. 



April If., 1912. Put one drop of 2% nicotin 

 into left eye of 9 at 10:40 a. m. Bird intoxi- 

 cated in 2 min. but revived in 5 min. Second 

 drop at 10:50: bird very "groggy" in 2 min.; 

 lay on its back in 3 min. breathing with 

 difficulty, dead in 4 min. ; widely dilated pupil 

 left; semi-dilated right. 



March 30, 1912, 3 :30 p. M. Put one drop of 

 1% nicotin into the left eye of three adult 9 . 

 All became more or less "wobbly" in two 

 minutes, recovering almost entirely in 15 

 minutes. At 4 p. M. the pupils, left, were all 

 three dilated ad max., although when exposed 

 to the diffuse light of a north room they con- 

 tracted; almost to normal in a very bright 

 light. At 4 :30 p. m. the pupils were all nor- 

 mal except one, left, pupil which was slightly 

 and continuously dilated, and not much 

 affected by strong light. Put one drop of a 

 two per cent solution of nicotin into left eye 

 of two adult 9 at 12 o'clock. One died in 

 15 minutes, under complete collapse. The 

 other became very stupid and laid on her 

 stomach for % hour, after which she revived 

 but was not as lively as before. At 2 p. m. 



the left pupil of living Sparrow was dilated 

 ad max, and but slightly affected by light. 

 Right pupil unaffected at 4 p.m.; both pupils 

 normal at 4 p. M. 



March 26, 1912. Examined pupils in one 

 c? and two 9 1H to 2^ mm. in diameter. 

 They contract promptly in light to 1 mm. 

 Nicotin, both 1% and 2%, seems to "daze" 

 the birds. One drop of each solution, put 

 into the right eye caused paresis of lower lid 

 but not of nictating membrane; dilation of 

 pupil in 20 min. to 4 to 5 mm., which re- 

 mained in this condition for at least 13^2 hours. 

 Left eye as before. In 2j^ hours pupils 

 normal again. Bright light focused on dila- 

 ted pupil caused a contraction to 3 mm. which 

 instantly recovered to 5 mm. on medium 

 illumination. After 1^ hours 2% nicotin 

 dilated right eye of 9 to 6 mm. and it was 

 then only slightly affected by bright light. 

 One drop of a 2% pilocarpin hydrochloride 

 put into left eye of 3 adult English Sparrows, 

 two 9 and one d", at 11:25 A. M., March 28, 

 1912. Negative results at 12:00. 



In other words, one per cent solution of nic- 

 otin brings about a dilation of the avian pupil 

 that persists for several hours, and is prob- 

 ably the best agent one can use for the 

 purpose. 



Experience has proved that the self-lumin- 

 ous, electric ophthalmoscope having a small 

 eyehole in a "split" mirror is the best instru- 

 ment for exploring the avian fundus. Such 

 an instrument is described in Chapter V, and 

 there depicted as Fig. 21. 



After a careful inspection of the anterior 

 parts of the eye, both without and with a 

 lens (to make sure that there is in the ob- 

 served eye no obstruction to an examination) 

 the observer should seat himself on a chair 

 in a dark room. Then, holding the instru- 

 ment against his own eyebrow with one hand 

 and a +20D. glass with the other hand, focus 

 the light from the ophthalmoscope, held at a 

 distance of about 40 cm., or 18 inches, from the 

 bird's eye, through the dilated pupil and upon 

 the fundus of the bird, firmly held by an 

 assistant seated opposite. 



In field work both the observer and his 

 assistant may kneel on the earth under a 



