36 GNATS on ^[OSQUITOES — CHAPTER II 



in the mixture will allow ; they are then placed on the 

 warm plate and the paraffin melted for a moment, after 

 which they are successively passed through baths of turpen- 

 tine, absolute alcohol, and 40 per cent, spirit, and are then 

 ready for staining. 



For this purpose I find no dye better than Hanson's 

 methylen blue (borax 5 per cent., methylen blue 2 per cent., 

 aqueous solution) ; this is allowed to act for several minutes 

 and then washed off with water, after which it is well to 

 give a ground staining of watery solution of eosine or 

 fuchsine. After staining the slides are passed successively 

 through baths of 90 per cent, spirit, absolute alcohol, and 

 turpentine ; and finally mounted in balsam. Gentian violet 

 also gives good, and Ehrlich's hsematoxylin fair, staining, 

 but I have not been able to get any result with borax- 

 carmine. Working in England I tiave not been able to 

 test this plan on infected Mosquitoes, but the perfect way 

 in which the most delicate tissue elements are preserved, 

 and the fact that it is so well suited to the use of Manson's 

 stain, makes it a hopeful method for demonstrating the 

 parasites in the salivary glands. Great care must be taken 

 to lose none of the series of sections, as the salivary glands 

 are so small that the}' may easily be missed unless the 

 series be fairly complete. 



As the majority of workers at tropical medicine must 

 necessarily conduct their investigations in places where 

 there is no gas supply, such as is required for the working 

 of the ordinary imbedding apparatus and other appliances 

 involving the employment of self-regulating appliances for 

 maintaining a constant temperature, it may not be out of 

 place to describe a simple piece of apparatus for the purpose 

 which I have used for many years in India. It consists 

 of a sheet of copper about 15in. long by Hin. broad and 

 at least -j^^^^- thick. This is supported in a horizontal 

 position on two wooden feet sufficiently high to admit of 

 the chimney of a small paraffin lamp being placed under 

 one end. 



In addition to the ordinary copper capsules for containing 

 the melted paraffin for imbedding, a special long narrow one 



