178 Appendix 



This is best done by using a wide-mouthed bottle fitted 

 with a cork bored with two holes. A straight glass inlet- 

 tube is passed through one hole down to the bottom of 

 the bottle. In the other is fitted a V-shaped outlet-tube. 

 which is not allowed to descend quite through the cork. 

 This allows a piece of copper gauze to be tacked over the 

 outlet-aperture, to prevent the objects being swept out 

 of the bottle. A current of water passing through the 

 bottle keeps the larvae gently moving about in the water. 

 Flemming's mixture, although an extremely faithful fixing 

 agent, often renders staining by haematoxylin methods 

 difficult, especially if the objects have not been thoroughly 

 washed. 



' 2. Perenyis chromo-nitric acid. Six hours are allowed 

 in this fluid. At the end of three hours the larvae are cut 

 in two. 70 per cent, alcohol is used for washing, and this 

 should be continued for twenty-four hours. After fixing, 

 the larvae may be preserved in 70 per cent, alcohol until 

 required. 



'staining and preparing for continuous sections. 



' Staining in hulk. From distilled water the larvae are 

 transferred to weak Delafield's haematoxylin solution. 

 They remain in this fluid until stained a uniform blue. 

 To determine this, the larvae must be occasionally exa- 

 mined with a pocket lens in distilled water. In about 

 a week they wiU probably be sufficiently stained. The 

 staining fluid is washed out by distilled water. After 

 dehydration the larvae are cleared in clove oil. From 

 absolute alcohol they are passed into a mixture of equal 

 parts of clove oil and absolute alcohol for half an hour, 

 and finally into pure oil for two or three hours. 



' Paraffin embedding. From clove oil the larvae are 

 transferred direct to the hard paraffin bath for six 

 hours. 



