THE ANATOMY OF THE ADULT MOSQUITO 99 



fallen to my lot to attempt. It is comparatively easy to 

 obtain a portion of them for microscopical examination, but 

 to lay them bare intact, and still more to follow out the 

 com-se of their ducts, is a task that will try the most patient. 

 For often, as Dr. Daniels remarks, all one has to show for 

 one's pains is the intra-glandular portion of a duct, denuded 

 of its cells. As however, it appears probable that it is 

 through the infection of these glands and their secretion that 

 the germs of malaria are carried to man, their structure and 

 relations require to be carefully studied. Although their 

 duct passes forward to open into the fundus of the hypo- 

 pharynx, these glands are rather closely bound down to the 

 oesophageal bulb on which they lie by means of connective 

 bands, and hence are occasionally brought away with the 

 rest of the digestive viscera in the dissection of the stomach ; 

 but such an occurrence is merely accidental and cannot be 

 relied on ; and where the glands are required for investiga- 

 tion, the following is the best method I can suggest for ex- 

 posing them : — 



Place the insect in some salt solution on a slide, and then, 

 with the point of an edged needle, lay open the narrow neck 

 connecting the head and thorax, keeping well to the dorsal 

 side. Next pass the needle into the midst of the thorax, 

 so that it must divide the oesophagus about the middle ; 

 then by a few gentle strokes, tear through the integuments 

 of the neck here and there, where it joins with the thorax, 

 still keeping away from the ventral side ; and finally, keeping 

 the left hand needle entangled in the thorax, gently tear off 

 the head with that held in the right and clear away the rest 

 of the insect. 



It is well at this stage to wash well with fresh salt 

 solution from a pipette, and it facilitates the recognition of 

 the various structures to just colour the solution with methy- 

 lene blue. 



If the separated head be now carefully examined there 

 will be seen, protruding from the torn neck, the tag of 

 oesophagus which has been drawn out from the thorax, and 

 round it several minute glistening lobular bodies, which, 

 under a sufficiently powerful lens, look much like tiny bunches 

 of grapes. 



