This section is from the book "The Natural Food Of Man", by Emmet Densmore. Also available from Amazon: How Nature Cures Comprising a New System of Hygiene.
"It has long been the opinion of scientific men, that by suitable diet and regularity the blessings of life may be enjoyed in fair health to a 'green old age.' The purpose of this work is to show that we may for a time curb the causes which are visible in effect as age advances, and thus prolong life; and, further, that by other means, founded upon simple fact, we may accomplish this for a lengthened period.
"The author's attempt to deal with a matter of such vast importance as the prolongation of life will necessarily subject him to severe and probably adverse criticism. In the first edition of a book hurriedly written in moments snatched from the turmoil of a general practice, many minor errors are sure to be found; but, as the author takes facts for a beacon, there is no error in principle. He will only ask those who criticise to imagine themselves for the time in the position of Astrea, the goddess of Justice, and not to weigh the evidence with one scale heavily laden with prejudice. . .
"With all our physiological, anatomical, and philosophical discoveries, there are left many questions at present not solved; amongst others, the action of the brain, thought, motion, life, and the possible prolongation of existence. Nature speaks to us in a peculiar language, in the language of phenomena. She answers at all times questions which are put to her; and such questions are experiments.
"In 'old age' the body differs materially from youth in action, sensibility, function, and composition. The active, fluid, sensitive, and elastic body of youth gradually gives place to induration, rigidity, and decrepitude, which terminate in 'natural death.' In nature there are distinct reasons for every change, for development, growth, decomposition, and death. If, with our minds free from theory, and unbiassed by hypotheses, we ask Nature the cause of these changes, she will surely answer us. Let us ask her the cause of these differences between youth and old age - why the various functions of the body gradually cease; why we become 'old' and die. The most marked feature in old age is that a fibrinous, gelatinous, and earthy deposit has taken place in the system; the latter being composed chiefly of phosphate and carbonate of lime, with small quantities of sulphate of lime, magnesia, and traces of other earths.
"Among physiologists and medical philosophers generally, the idea prevails that the 'ossification' (or the gradual accumulation of earthy salts in the system) which characterises' natural death' is the result of 'old age,' but investigation shows that such an explanation is unsatisfactory. For, in the first place, if 'old age' (which is really the number of years a person has lived) is the cause of the ossification which accompanies it, then, if 'like causes produce like effects,' all of the same age should be found in the same state of ossification; but investigation proves beyond all doubt that such is not the case. How common it is to see individuals about fifty years old as aged and decrepit as others at seventy or eighty! . . . .
"We now come to the most important change of all, which fully accounts for the many differences in the brain existing between youth and old age, that is, the changes in the blood-vessels supplying it. The arteries in old age become thickened and lessened in calibre from fibrinous, gelatinous, and earthy deposits. This is more easily detected in the larger vessels; but all, even to the most minute subdivisions, undergo the same gradual change. Thus the supply of blood to the brain becomes less and less; hence the diminution in size of the organ from the prime of life to old age; hence the functions of the brain become gradually impaired; the vigorous brain of middle life gradually giving place to loss of memory, confusion of ideas, inability to follow a long current of thought, notions oblivious of the past and regardless as to the future, carelessness of momentary impressions, softening of the brain, and that imbecility so characteristic of extreme age."
After quoting from Copland, Hooper's "Physician's Vade-Mecum," and from the experiments of M. Rayer, M. Cruveilheir, M. Rostan, M. Recamier, and others, Dr. Evans continues:
"We have quoted from the above authorities to show that ossification and thickening of the arteries of the brain has not been overlooked, but that it is a fact which has been known for many years; also to show that this gradual process of ossification is not due to any inflammatory action. And we shall show that this earthy matter has been deposited from the blood, and increases year by year with old age, thus lessening the calibre of the larger vessels, partially, and in some cases fully, 'clogging up' the capillaries, gradually diminishing the supply of blood to the brain, causing its diminution in size in old age, and fully accounting for the gradual loss of the mental capabilities before enumerated.
"As age advances, the energies of the ganglial system decline; digestion, circulation, and the secretory functions are lessened; the ganglia diminish in size, become firmer, and of a deeper hue. In old age the nerves become tougher and firmer, the medullary substance diminishes, and their blood-vessels lessen in calibre. The sensibility of the whole cerebro-spinal system decreases, hence diminution of the intellectual powers, lessened activity and strength in the organs of locomotion in advanced age."
I quote further, from pages 27 and 28:
"In the foregoing pages we have pointed out the differences existing between youth and old age. In the former the various organs and structures are elastic, yielding, and pliable; the senses are keen, the mind active. In the latter, these qualities are usurped by hardness, rigidity, and ossification; the senses are wanting in susceptibility, the mind in memory and capacity.
"Further, that these changes are due, firstly, to a gradual accumulation of fibrinous and gelatinous substances; secondly, to a gradual deposition of earthy compounds, chiefly phosphate and carbonate of lime. These, acting in concert, diminish the calibre of the larger arterial vessels, and by degrees partially, and sometimes fully, obliterate the capillaries. By these depositions every organ and structure in the system is altered in density and function; the fluid, elastic, pliable, and active state of body gives place to a solid, inactive, rigid, ossified, and decrepit condition. The whole system is 'choked up'; the curtain falls, the play of life is ended, terminating in so-called 'natural death.'