92 NATURAL SCIENCE [August 
language, and please observe the use of the word “ degeneration ” 
is thus avoided. 
The structural changes in the gerontic stage of the individual 
are repeated with sufficient accuracy in the adult, and often even in 
the younger stages of types that occur in the decline of the evolu- 
tion of a phylum, so that one is forced to consider seriously whether 
they may not have been inherited from types that occur at the acme 
of the same group. The fact that these changes occur first in the 
individual during the gerontic stage does not necessarily imply that 
they first make their appearance after the reproductive period. No 
gerontic limit is known to the reproductive time in the lower 
animals, and it may well be that the continual recurrence of 
gerontic stages in individuals during the epacme of groups may 
lead to their finally becoming fixed tendencies of the stock or 
hereditary in the phylum, and thus established as one of the 
factors that occasion the retrogression or decline of groups. The 
decline may also be considered as occasioned by changes in the 
surroundings from favourable, as they must have been during the 
progression up to acmatic time, to unfavourable during the succeed- 
ing declining period in evolution. Still a third supposition is also 
possible, viz., that the type, like the individual, has only a limited 
store of vitality, and that both must progress and retrogress, complete 
a cycle and finally die out, in obedience to the same law. 
All of these views can be well supported, but, whatever may be 
the true explanation, it is obvious that there are plenty of declining 
types, which, in their full-grown and even in their adolescent 
stages, correlate in characters and structures with the characters 
and structures that one first finds in the transient old age or 
gerontic stages of acmatic forms of the same type. These can, 
therefore, be truthfully and accurately described as phylogerontic 
or old in the phylum. 
The position of man is at the extreme end of a series of con- 
verging lines in his own stock. This is also indicated by his 
structure and development which is phylogerontic, and it is 
therefore of the highest importance for him to avoid all move- 
ments tending to the increase of his natural and possibly inherent 
tendencies towards retrogression. The approximation of the sexes 
in habits of body or mind is therefore to be avoided, as possibly 
leading to convergence of the progressive characters non-existing 
between the sexes and the inauguration of retrogressive evolution. 
It is hoped that no pretence of being able to solve problems 
requiring such vast knowledge and many-sided considerations will 
be attributed to this article, which has been intended simply to call 
attention to the scientific side of the question. It seems obvious 
that the time has come when thoughtful men and women should be 
