APPENDIX. 



DIEECTIONS FOE COLLECTING AND 

 PEESEEVING FISHES. 



Whenever practicable fishes ought to be preserved in spirits. 



To insure success in preserving specimens the best and 

 strongest spirits should be procured, which, if necessary, can be 

 reduced to the strength required during the journey with water 

 or weaker spirit. Travellers frequently have great difficulties in 

 procuring spirits during their journey, and therefore it is advis- 

 able, especially during sea voyages, that the traveller should take 

 a sufficient quantity with him. Pure spirits of wine is best. 

 Methylated spirits may be recommended on account of their 

 cheapness ; however, specimens do not keep equally well in this 

 fluid, and very valuable objects, or such as are destined for 

 minute anatomical examination, should always be kept in pure 

 spirits of wine. If the collector has exhausted his supply of 

 spirits he may use arrack, cognac, or rum, provided that the fluids 

 contain a sufficient quantity of alcohol. Generally speaking, 

 spirits which, without being previously heated, can be ignited by 

 a match or taper, may be used for the purposes of conservation. 

 The best method to test the strength of the spirits is the use of 

 a hydrometer. It is immersed in the fluid to' be measured, and 

 the deeper it sinks the stronger is the spirit. On its scale the 

 number signifies what is called proof spirit, the lowest 

 degree of strength which can be used for the conservation of fish 

 for any length of time. Spirits, in which specimens are packed 

 permanently, should be from 40 to 60 above proof. If the 

 hydrometers are made of glass they are easily broken, and there- 

 fore the traveller had better provide himself with three or four 

 of them, their cost being very trifling. Further, the collector 



