Practical Course, 99 
- DISSECTION OF THE SPARROW % 
“To make out the essential features of bird structure a sparrow (Passer 
domesticus) may conveniently be taken. Sparrows are excessively com- 
mon in Dehra. They are best caught alive with nets, Any number 
can be killed in a few minutes by putting them into a closed earthen 
gumila and pouring in some chloroform. . The ordinary native name for 
the sparrow is gauriya. Notice that the body is almost completely 
covered with feathers. The specimens will be found to be of two 
kinds :— 
(1) Males, with a black patch on the throat and in front of the 
mouth. . 
(2) Females, where these markings are replaced by grey, which is 
far less conspicuous. 
In the head examine— 
(1) The large laterally-placed eye with its upper and lower movable 
eye-lids, and the third eye-lid (nictitating membrane), 
which lies in the anterior angle of the eye-and can be 
yapidly drawn over the eye itself. Pull the nictitating 
membrane over the eye with your forceps and notice how 
it works, 
(2) The beak, formed by horny sheaths covering the upper and the 
lower jaw, which are both toothless. 
(3) The nostrils, which are a pair of slit-like holes situated on 
either side at the base of the beak communicating with 
the mouth behind. 
(4) The ears, which appear as circular holes in the sides of the 
head behind and below the eyes, They are covered with 
a cirelet of small feathers. 
Cut down the sides of the mouth with your scissors, so as to increase 
the extent to which it can be opened, and make out:— 
(1) The pointed tongue, which lies in the floor of the mouth. 
(2) The large median slit-like opening in the roof of the mouth 
communicating with the nostrils. 
(3) The small median opening immediately behind the large one. 
This opening is the termination of the eustachian tubes, 
which place the mouth in communication with the inter- 
nal cavity of the ear on either side. 
(4) The continuation of the mouth behind into the csophagus, 
_ down which the food passes into the crop. 
(5) The median slit-like opening which lies behind the tongue 
and communicates with the windpipe (trachea), through 
which the air passes into the lungs and air-sacs. 
1 It may be necessary to curtail or omit this dissection for want of time. 
H 
