REPORT ON MOSQUITOES. 77 



Another method recommended is to remove everything except 

 the thorax and abdomen and to separate the last two segments of 

 the latter. Then by gradually pulling on these and holding the 

 thorax by the base of the forelegs the alimentary canal will be 

 drawn out. If the stomach alone is wanted, the same method 

 may be pursued with the abdomen alone, or after removing the 

 abodmen, the stomach may easily be worked out. 



The salivary glands — also appendages of the alimentary canal 

 — are situated in the fore part of the thorax, below and on either 

 side of the alimentary canal just above the forelegs, and they 

 consist of three lobes on each side. From each group of lobes 

 there extends a duct v^'hich joints its fellow to form a common 

 duct, which passes forward and enters the fore part of the gullet 

 or oesophagus. To dissect out these glands, cut away everything 

 except the head and the fore part of the thorax. Carefully pick 

 off the upper surface of the latter and gently pull the head away; 

 holding fast to the lower part of the thorax. When this is done 

 the glands will generall)^ be drawn away with the head and then 

 by carefully cutting very close to the head the glands will be 

 removed with other material. They can be separated with a 

 little care and practice, although I find it rather difficult to secure 

 both glands together. 



Permanent mounts of the internal structures cannot be made 

 satisfactorily by any method that we know of without contract- 

 ion occurring. Grassi recommends conditionally, two per cent, 

 commercial formaline in 75-100 per cent, salt water. In this 

 case the cover slip must be ringed with a cement. Grassi also 

 suggests a fluid consisting of white of ^%^, 1-5 grains of salt 

 and 250 grains of water. The material is beaten and filtered. 

 The object in the fluid is placed on a slide, fixed in osmic acid, 

 and mounted in glycerine.* 



For staining, picro-carmine, eosin or nigrosin will be found 

 useful, and I have had some good results with the latter. If the 

 first method of mounting is used, the stain may be run under the 

 cover slip and afterwards glycerine added, or as Berkeley recom- 

 mends, I per cent, carbolic acid in glycerine. The cover may 

 then be ringed. 



The preparation of paraffine sections or similar work does not 

 come within the scope of this volume. For this work and other 

 microscopical preparations, Lee's Vade Mecumf should" be con- 

 sulted. 



* Quoted from Berkeley previous!}- cited. 



fThe Microtomist's Vade-Mecum, \)y Arthur Bolles Lee. J. & A. Church 

 Great Marlborough street, London. 



