NO. 42. — 1891.] ZOOLOGICAL SPECIMENS. 



71 



carbolic acid mix with it ? I found on experimenting that, 

 carbolic acid mixed with it in all proportions. There was 

 of course, no idea of using this as a preservative, the specimens 

 must be first prepared. Very fluid arsenic paste was used 

 for silvery fish with some success, and reduced gum and 

 glycerine and gelatine — of which K is an example — was also 

 tried ; but from the very first it proved a very refractory 

 mounting medium. It was very difficult to get a sufficiently 

 white oil to begin with, and when I did, it always had a 

 strong tendency to discolour. Time has proved that I need 

 not have troubled myself : it cannot be used as a mounting 

 medium. Mixtures of carbolic acid and glycerine, or 

 cocoanut oil, attain a deep colour in time, irrespective of any 

 animal matter in them. L shows the action in the case of 

 glycerine ; M in the case of oil. You will see in this latter 

 case that the toad is in splendid preservation, and the fluid 

 bright and clear, but the colour is very objectionable. 

 Whole cases filled with bottles of this tint would be very 

 ugly, although, if the animals and their colour were well 

 preserved, they might perhaps be more instructive than 

 ordinary specimens. There was, however, another difficulty : 

 a very fine cobra, well hardened in spirit after some months, 

 broke down from no apparent cause. It was also found 

 impossible to get a common bloodsucker mounted in this 

 medium. Neither gum and glycerine nor strong spirit, nor 

 arsenic paste, nor anything else would keep them. In fact, 

 the medium appeared either not to be safe or not universally 

 applicable. In order to study it and learn what its action 

 really was, I preserved a bloodsucker in it direct, without 

 previous preparation of any kind, and found that I had a 

 preservative of form as good as any known, and of colour as 

 good as gum and glycerine itself. In this case the carbolic 

 acid is either the dehydrator or, perhaps, combines with the 

 tissues and preserves them, whilst the oil acts as the atmos- 

 pheric excluder ; and now you will see why difficult subjects 

 such as cobras and bloodsuckers, previously prepared, broke 

 down. The tissues had absorbed from the alcohol or arsenic 



