- 31 — 
alterations ; and the nuclei, for instance, can no longer as a rule be differentiated by 
staining methods. There are exceptions to this rule, for some nuclei are noticeable still, 
as in the epidermic layer of the skin, the connective tissue of the female breast, the 
adenoid tissue of the intestine, and the cells of some livers and kidneys. Moreover there 
is reason to think that the nuclei are really better preserved than I imagined and that 
an improved technique will reveal their presence more often. 
The histological details of the cells of most organs have also almost entirely 
vanished ; this is specially well marked in the liver and kidneys, where the individual 
cells are often undistinguishable. On the other hand, the histological characteristics of 
certain bloodvessels, of the nerves, of the heart and specially of muscle, are surpris- 
ingly well preserved. 
1 think therefore that the microscopical examination of mummies may reveal 
changes due to infiltration of tissues by: l" New growths, 2» Infective granulomata, 
3° Animal and vegetable parasites, 4" Inflammation, 5» Proliferation of connective tissue 
(cirrhosis), 6"^ Atheroma and Calcification, but that there is little hope of recognising 
diseases in which the chief lesions are seen in the cells of organs and tissues. 
An attempt may now be made to answer another question, partly at any rate. 
Does the histological structure of mummies give any indication with regard to the 
method of preservation of the body and organs in the XXIst dynasty? 
In describing the bloodvessels, I drew attention to the fact that as several hours 
elapsed between the time of death and the removal of the organs from the body, a certain 
amount of decomposition must necessarily have taken place. 
When enumerating the details of the histology of the skin, the difference in 
the state of preservation between the skin of the trunk and that of the extremities was 
insisted on. This difference is probably due to cadaveric putrefaction, always beginning 
earlier and being more marked in the trunk than in the extremities. 
The exact nature of the pickling solution has not been ascertained, but I 
feel inclined to think that it contained a large quantity of chloride of sodium. 
Strong solutions of chloride of sodium have a light macerating action, and the salt 
extracting water from the tissues causes the latter to shrink, and diminishes or even 
abolishes putrefaction. Indeed chloride of sodium has been used from time immemorial 
for preserving food stuff. On the other hand, natron is used in histology chiefly for the 
preparation of alkaline solutions of dyes, and for the maceration of tissues. A weak 
solution of such a salt would not preserve tissue, while a strong one would macerate 
them past all recognition. 
It appears to me probable that the solution used was one of « natron », but that 
this « natron » consisted chiefly of sodium chloride with a small admixture of carbonate 
and sulphate of soda. It would be interesting to ascertain whether samples of « natron » 
with such a chemical composition are still to be found in Egypt. 
After the organs were removed from the pickUng bath, the dryness of the atmos- 
