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different functions and shapes. This cannot be due to the 
chromosomes and genes, for all the cells are equally endowed, 
but it must be due to forces external to these chromosomes, by 
which some of the latent capacities of growth are suppressed, 
while others are encouraged. Some light is being thrown upon 
this most interesting problem by recent discoveries in cell activi- 
ties and harmones, and in the harmonic relationship of various 
parts of an organism. This most important and fascinating sub- 
ject is but in its infancy, but already it appears to have thrown 
some little light upon Lamarckian factors and the inheritance of 
acquired characters. The post-pituitary harmone is responsible 
for the change of color in the skin of the frog which is of a 
protective nature, and, if we accept Kammerer’s experiments, 
individuals born of parents that have lived in dark or light sur- 
roundings are correspondingly light or dark, which most likely 
is caused by the influence of the harmones on the germ plasm. 
Guyer and Smith’s experiments on the eyes of rabbits may also 
be due to similar influences. Along this line of thought we may 
eventually find the mechanism by which we can understand, to 
some extent, the effect of use and disuse upon the organism. 
But we must co-ordinate the studies of form, function and 
development, or morphology, physiology and embryology. 
This subject also has direct bearing upon the subject of this 
address, viz., Homoplasmy, for if environment in its widest 
meaning can affect certain organs or characters in one animal 
it is likely to do so in many others. The reduction of eyes in 
cave-dwelling animals may then be due to the absence of stimuli 
and not to “chance throws of the Mendelian dice”; and if we 
admit the possibility or probability of this, then the reduction 
of organs in parasitic animals may also be due to the absence 
of stimuli. And then it is not a long step to the production of 
similar characters in different animals living under similar con- 
ditions. That they do develop such is common knowledge. The 
question at present at issue is whether this is due to harmonic 
relationship between the animal and its environment or to ‘chance 
throws of the Mendelian dice.” 
