e duration of the new youth should be another span of life,
whereas in actuality it is only a fraction of that time. This fact,
together with a number of others, make clear that while the gonads may
be the jeune premier of the drama, the vitality of the plot depends
upon the other endocrines. Since old age is an exhaustion, permanent
and irreparable of _all_ the members of the ductless gland
directorate, the reason becomes clear for the temporary quality of the
rejuvenation effected by the procedures of Steinach.

Practically, then, the question at once arises: which of the glands in
particular are involved? There is first that ubiquitous agent in the
system, the thyroid. Chemical analysis of it has shown that the
iodine content decreases with the age of the individual, and becomes
specially low after forty. It is after the menopause in women that
myxedema, the disease of complete degeneration of the thyroid, and of
the physical and mental faculties, is most frequent. The thyroid
of old people exhibits, in varying degrees, signs of a similar
degeneration. Thyroid feeding, properly controlled, will clear up
certain of the deteriorations of mind and body observable in the aged.
The grossness of the features lessens, a number of the pains go,
muscular endurance increases, memory and intelligence do not remind
one so forcibly of the old dotard in his second childhood. Of course
the improvement at present achievable is only relative. But in the
prematurely aging, decay invading a half accomplished maturity,
marvels have been achieved at times with feeding of the gland.

The pituitary, too, begins to retrogress after the period of maturity.
And an early retrogression means a short maturity. In women, the onset
of an obesity, and coincidently, of a lazy and dull morale, coincides
with this declension of the pituitary powers. All the glands of
internal secretion, in fact, shrink and shrivel as old age advances.
Only, as in other relationships, the predominating endocrine stamps
its signature more visibly upon the documents of decadence than the
others. Pituitary types, as said, get fat and slow, thyroidal become
bulky and stupid or thin and sour, the adrenal dark, shrunken and
forever tired of life. So type emerges, even in all-around glandular
deficiency.

The problem of rejuvenation is the problem of recharging, or replacing
all of the glands of internal secretion, at least the most important,
the thyroid, the pituitary an