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to us, any perturbations which could be explained on the supposition of such 
a planet existing would be no absolute disproof of gravitation — 
The Chairman. — Except that no one has told us that such a thing is 
possible as a revolving planet which should not reflect light. 
Mr. Warington. — If you take so simple a substance as lampblack, and 
properly prepare it, you will find it reflects no light at all — 
The Chairman. — Newton found nothing like this in his experiments. 
Mr. Warington. — Well, as to the total absence of reflection, I may be 
straining the matter too far ; but of this I feel sure, that were there a planet 
coated with lampblack at the distance of Neptune, it would be invisible to us, 
and that would answer my purpose quite as well — 
The Chairman. — I should consider things like that to be among the im- 
probabilities of nature. 
Mr. Warington. — Now see what has been the result of this misunder- 
standing about my illustration. Not only has Mr. Reddie gone out of his way 
to refute universal gravitation, but he has entirely missed the real object of 
the illustration ; and so when he comes to use the terms technically, as I used 
them, and in reference to my paper, it is in a totally different sense, just 
because he has been so absorbed in refuting, as he thought, the substance of 
what I said about gravitation, as entirely to overlook its true bearing on the 
matter in hand as an illustration of my meaning in the use of these terms. 
Then in Mr. Reddie’s remarks about my definition of u species,” there is 
again unfairness. Mr. Reddie writes thus, quoting my definition : “ A 
species is a race of living beings possessing common characteristic differences 
from all others, which differences at the present time are constant and 
inherent .” In the next sentence he leaves out the word u differences,” and 
tells you, “ It is admitted that at the present time the characteristics of 
species are constant and inherent.” I said nothing of the kind. Then what 
use does Mr. Reddie make of this ? He says that the proposition I put for- 
ward is inharmonious, because my definition of species contradicts the theory. 
(Hear, hear.) Is there any contradiction ? No. I have not said that all 
the characteristics of the plant or animal are constant and inherent, but that 
the characteristic differences of the species are so — a very different thing 
indeed. To give an illustration : Heat and light are convertible things ; no 
one would dispute it for an instant. You can change light into heat, or heat 
into light — 
Mr. Reddie. — I must dispute it. You may do it sometimes, but not 
always. As a rule, you cannot. 
Mr. Warington. — I simply say the thing can be done. If, now, I wanted 
to define heat, I should certainly put in my definition some clause excluding 
light ; and if I wanted to define light, I should in like manner exclude heat ; 
and I should say that these points constitute the characteristic differences of 
light and heat. I should also say they are constant and inherent — that they 
cannot change ; for if they change, then the heat is no longer heat, the light no 
longer light. (Hear, hear.) So with species : if the characteristics of species 
vary and are uncertain, then those characteristics thereby at once cease to be 
