348 APPEXDIX TO CHAPTERS VI. TO LX. 



The best method is Lang's picro-carmine and eosin.* The 

 eosin in some way acts as a carrier for the carmine, and is 

 afterwards washed out with 70 per cent., and then with abso- 

 lute alcohol. 



It is impossible to over-stain, and the nymph should be left 

 from four days to a week in the stain. 



My friend, Brigade-Surgeon Scriven, has been indefatigable 

 in preparing serial sections of nymphs, which he has very 

 kindly placed at my disposal, and he adopts the above method 

 most frequently. His specimens are very beautiful and definite, 

 and I take the present opportunity of thanking him for his 

 valuable assistance. 



Viallanes used collodion as a material for imbedding the 

 nymph, and I have obtained very fair results from its use. I 

 am not, however, prepared to recommend it for serial sections, 

 and I have not found it to possess any advantages over paraffin. 

 When celloidin or collodion are used, either for imbedding, or for 

 collodionising paraffin sections, oil of cloves should not be used 

 as a clearing agent. Equal parts of xylol and solid carbolic acid 

 may be employed instead, but the slides must be well washed 

 with xylol to remove all traces of carbolic acid before they are 

 finally mounted with balsam. 



The details of these processes and much valuable information 

 on technique will be found in the second edition of the ' Micro- 

 tomist's Vade-Mecum,'t which is a far better work than the 

 first edition, from which I formerly quoted. 



The outer covering of the pupa or embryo is easily removed 

 with a little practice. Perhaps the best method is to cement 

 the eggs or pupa; to a slide with gum or shellac in creasote ; 

 the outer covering can then be cut with a sharp needle, and the 

 embryo or nymph removed. This must be done under dilute 

 alcohol — 50 per cent, is sufficient — with a dissecting micro- 

 scope. 



* Equal parts of a solution of picro-carmine, Weigert's or Ranvier's, and 

 a 2 per cent, aqueous solution of eosin. 



t 'The Microtomist^s Vade-.Mecum,' by A. Bolles Lee, second edition, 

 London, 1890. 



