128 GY. LAONEL TAYE [AUGUST 
there is always a certain excess force, which would be fostered by 
selection, sufficient to provide for emergencies. 
9. Rudiments and their disappearance.—It is assumed that there 
will come a point where the rudiment will be of such slight significance 
that it will no longer be of selection value, hence it is urged that the fact 
that rudiments do tend to completely disappear, is against any purely 
selectionist principle. Leaving out of consideration the possibilities of 
reversal of selection, panmixia, etc., it appears to me that there is a 
comparatively simple cause for this disappearance. George Henry 
Lewes, Wilhelm Roux, and more recently Weismann, have all fallen 
back on the assumed necessity of applying the principle of selection to 
the several parts and specialisations of the individual organism, in 
addition to the action of selection on the whole organism. The last 
writer in particular, in his “Germinal Selection,” suggests that a 
struggle among the different parts of the germ-plasm may account 
for the complete disappearance of rudiments, this germinal selection 
thus supplementing the action of panmixia, personal or organismal 
selection, etc. Now the necessity for increased co-ordination of 
parts with increasing specialisation, entailing, as it necessarily must, 
an increasing mutual dependence of each part on the others, must lead 
as the type advances to diminished opportunity for any struggle of 
parts in the organism, consequently if such a struggle exist at all it 
must be limited to the most undifferentiated organisms. I do not 
therefore see how this principle can explain the disappearance of rudi- 
ments in any of the more specialised organisms, hence it does not seem 
to be sufficient answer to the above-mentioned difficulty. In the 
development of the individual we see a disappearance of structures, 
which appear to become with advancing development useless, almost 
parallel to the gradual disappearance of rudiments, etc., in the history 
of the species evolution. And a common explanation for both of these 
series of phenomena can, I believe, be satisfactorily found in the known 
facts of nutrition. Growth of any tissue would seem to depend on 
three conditions, a stimulus of the part adequate to promote func- 
tional activity, a proper food supply, and efficient removal of products 
produced by that particular tissue’s activity. There is abundant 
evidence to prove that a tissue tends to degenerate if its own excretory 
products are not removed; the evil effects produced by fatigue products 
in muscle and other tissues on the activity of the tissue itself prove 
that this factor must be of great importance wherever it is found to 
occur. Just as the growth and development of bacteria is interfered 
with, and finally altogether checked by the accumulation of products of 
their own activity, so a tissue in the higher organisms has its activity 
impaired and its power lessened when for some reason diminished 
elimination of its own metabolic products occurs. Now both in the 
development of the individual and the race we see an alteration of 
structure, a graduai transition from the less to the more specialised, 
