Appendix i8i 



will soften and adhere to the slide. Before removing 

 from the dish, add by means of a pipette a few drops 

 of 95 per cent, alcohol, and then submerge the slide in 

 spirit of the same strength in a dipping-bottle. Clear by 

 transferring to a mixture of one part absolute phenol with 

 four parts xylol. Entire larvae may be cut by this process 

 if plenty of time is allowed for staining and embedding.' 



MOUNTING or ENTIRE LAEVAE. 



Mr. J. J. AVilkinson, of Skipton, gives the following Mr.wiikin- 

 instructions for mounting aquatic larvae whole without thod of 

 pressure. Many of his j^reparations are extremely useful "Xre '"^ 

 for anatomical study, as the internal organs can be ex- 

 amined microscopically in situ. For some reason which 

 we can only guess at, the Chironomus-larvae hitherto put 

 up are not quite so successful as others, but they have 

 yielded good results. Perhaps the best proportion of 

 alcohol and ether has not yet been exactly determined. 



' Select transparent specimens, place them alive in clear 

 water, and keep them without food for a day or two, so as 

 to empty the alimentary canal. Have ready a number of 

 small, wide-mouthed bottles, containing a suitable mixture 

 of absolute alcohol and ether. If larvae are put into 

 alcohol alone they shrink, as exosmose is greater than 

 endosmose. In a mixture which contains too much ether 

 the case is reversed, and the larvae will swell until they 

 burst. From 15 to 20 per cent, of ether is suitable for 

 most larvae, but those of Chironomus will not bear more 

 than 10 per cent. AVhen all is ready, put a larva into 

 a watch-glass containing the mixture, and hold it in the 

 desired position with two small sable brushes. As soon 

 as it is set (that is, in from three to ten minutes, according 

 to size), transfer it to one of the bottles containing the same 

 mixture. Leave it for a few hours (or days, if more con- 



