io6 



When an excess of fluid is present, slide off the cover- 

 glass. The flattened mid-gut will probably remain 

 attached to the coverglass. 



Wash in water, and stain lightly with methylene 

 blue. Wash in water and allow to dry. Warm 

 gently to ensure complete dryness, and place the 

 coverglass, mid-gut downwards, upon a drop of balsam 

 upon a slide. 



The muscular fibres and other structures of the 

 mid-gut will be well exhibited. The zygotes will be 

 stained rather a dark blue. If not too darkly stained, 

 the pigment of the zygotes will have the appearance 

 it had in the fresh specimen. 



Method 3. For more minute histological examina- 

 tion, imbed the stomachs, or the whole mosquito, in 

 paraffin (p. 46). 



To DISSECT OUT THE SALIVARY GLANDS 



This is quite a simple proceeding if it be remem- 

 bered where they lie. They are intra-thoracic 

 structures, and they commence at the hinder portion 

 of the neck and end opposite the first pair of legs. 

 They lie ventrally, in fact, roughly speaking, they lie 

 just above the origin of the first pair of legs (Fig. 42). 



The simplest and most rapid method, and the one 

 that hardly ever fails, is the following : 



1. Place the mosquito in a drop of salt solution 

 on its right side, with the head pointing towards you, 

 as you dissect. 



2. Place the needle of the left hand on the thorax 

 to steady it, and place the needle of the right hand 

 on the back of the head and make steady gentle traction. 



3. If done carefully, it will be seen that the head 

 has pulled out a little mass of white tissue from the 



