698 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.41. 



Since it is the oxygen of the atmosphere and the accidental acids in 

 the latter that attack the more complex molecules of matter, acting 

 the more intensely the greater the humidity of the atmosphere, our 

 aim, for the purpose of preservation, should be absolute exclusion of 

 air and moisture. This atmospheric attack, combustion, or destructive 

 metabolism, however it may be called, begins in organic life with the 

 formation of the first ceU and does not end until the last particle of 

 bone has been disintegrated and oxidized into its component oxides. 

 This is the course of nature, wdiatever the length of time, be it a few 

 weeks or a million years. Silicification and carbonization as well as 

 a complete replacement by calcium carbonate will, for the purpose of 

 preservation, probably be always out of question. Infiltration of 

 fluid calcium carbonate would be very slow and would probably 

 change the external form while filling by accretion the cavities and 

 capillaries, within and mthout, proving this method to be vWioUy un- 

 rehable. 



There remains, therefore, as far as can be ascertained at the present 

 time, only the one method, and that is the exclusion of air and 

 humidity, and with it the forces of expansion and contraction. Wlien 

 life or vital forces no longer offset destructive metabohsm, the latter 

 wiU continue unchecked so long as external conditions promote the 

 process. The same atmospheric air that consumes the worn-out 

 tissues to furnish heat will continue to do so when heat is no longer 

 necessary. As it is desirable to preserve museum specimens, our aim 

 must be to check this combustion by the exclusion of the fuel neces- 

 sary for its support. 



That exclusion of air is an absolute preservative has been proven 

 by the thousands of perfectly preserved insects and other animal 

 inclusions in amber that have stood the test of thousands, if not of 

 millions, of years. Of all the substances known and considered so 

 far for the purpose of preserving bones and teeth not one is free from 

 objections, not one even produces absolute homogeneity or absolutely 

 excludes the air. 



Among the expedients considered is the method of leaving within 

 the bone a part of its organic and fatty substance as a preservative, 

 a method that at first gives a better appearance as well as a sub- 

 stantiality to the delicate portions that are not evident when the full 

 amount (50 per cent) of organic matter is withdrawn. 



Tliis might be satisfactory if it were possible to guard against 

 changes of temperature and the entrance of air and moisture. This 

 organic tissue within the pores of the bone, honeycombed (micro- 

 scopically) by the taxidermic processes of treatment, offers ready 

 admission to air and moisture, and as soaps or alkaline oxides, car- 

 bonates or borates, whatever may have been used, add nothing 

 preservative in place of the substances removed, but rather assist 



