Cope. ] 26 2 . [Dee. 15; 
selection, being no explanation. It has been shown by Bennett that the 
chances of such modification arising out of the many possibilities are ex- 
ceedingly small. 
If the above positions be trae, we have here also the theory of the 
development of intelligence and of other metaphysical traits: In accord- 
ance with it, each trait appropriates from the material ‘world the means 
of perpetuating its exhibitions by constructing its instruments. These 
react by furnishing increased means of exercise of these qualities, which 
have thus grown to their full expression in man. 
CRITIQUE. 
1. On the preceding essay.—There will probably be found to be consid-+ 
erable resemblance and coincidence between the theory of Use and Effort, 
and the Lamarckian view of Development. The writer has never read 
Lamarck in French, nor seen a statement of his theory in English, except 
the very slight notices in the Origin of Species and Chambers’ Encyclo- 
peedia, the latter subsequent to the first reading of this paper. 
Darwin’s only speculations as to the origin of new structures which are 
contained in his ‘‘ Origin of Species”? (Ed., 1860), so far as I can find, 
occur in the first and fifth chapters. In the first he says, discussing the 
variability of domesticated animals and plants, ‘‘ I think we are driven 
to conclude that this greater variability is simply due to our domestic 
productions having been raised under conditions of life not so uniform as, 
and somewhat different from, those to which the parent species have 
been exposed under nature. There is also, I think, some probability in 
the view. propounded by Andrew Knight that this variability may be 
partly connected with excess of food. * * * But I am strongly in- 
clined to suspect that the most frequent cause of variability may be at- 
tributed to the male and female reproductive elements having been 
affected prior to the act of conception. * * Nothing is more easy than 
to tame an animal, and few things more difficult than to get it to breed 
freely under confinement, even in the many cases where the male and 
female unite,’’ etc. Chapter V. repeats similar propositions but states 
that the effect of climate he believes to be small, but rather greater in 
plants than animals, 
The view as to the impressibility of the reproductive element is taken 
up by Mivart, but the subject remains in the chaos of unshaped hy- 
potheses. 
2. On the Origin of Genera.—The memoir issued by the writer under 
the above name was chiefly devoted to the demonstration of the law of 
Acceleration and Retardation. A small portion was devoted to geograph- 
ical and geological relations. It remains to correct two errors in the 
former portion of the book. 
(1). It is there stated (p. 5) that the Law of Natural Selection of Dar- 
win is as follows: ‘‘ That the will of the animal applied to its body in the 
search for means of subsistence and protection from injuries, gradually 
produces those features which are evidently adaptive in their nature. 
