Quote 25
I knew myself, at the first breath of this new life, to be more wicked, tenfold more wicked, sold a slave to my original evil; and the thought, in that moment, braced and delighted me like wine. I stretched out my hands, exulting in the freshness of these sensations; and in the act, I was suddenly aware that I had lost in stature. (10.4)
When Jekyll says he has "lost in stature," it is a pun. The phrase has two meanings: one, that he’s physically shorter; and two, that he’s not a nice, respectable man anymore.
Quote 26
I must here speak by theory alone, saying not that which I know, but that which I suppose to be most probable. The evil side of my nature, to which I had now transferred the stamping efficacy, was less robust and less developed than the good which I had just deposed. Again, in the course of my life, which had been, after all, nine tenths a life of effort, virtue and control, it had been much less exercised and much less exhausted. And hence, as I think, it came about that Edward Hyde was so much smaller, slighter and younger than Henry Jekyll. Even as good shone upon the countenance of the one, evil was written broadly and plainly on the face of the other. Evil besides (which I must still believe to be the lethal side of man) had left on that body an imprint of deformity and decay. And yet when I looked upon that ugly idol in the glass, I was conscious of no repugnance, rather of a leap of welcome. This, too, was myself. It seemed natural and human. In my eyes it bore a livelier image of the spirit, it seemed more express and single, than the imperfect and divided countenance I had been hitherto accustomed to call mine. And in so far I was doubtless right. I have observed that when I wore the semblance of Edward Hyde, none could come near to me at first without a visible misgiving of the flesh. This, as I take it, was because all human beings, as we meet them, are commingled out of good and evil: and Edward Hyde, alone in the ranks of mankind, was pure evil. (10.6)
Dr. Jekyll argues that Mr. Hyde is the perfect physical embodiment of the evil in his (Dr. Jekyll’s) character. In other words, Mr. Hyde looks evil.
Quote 27
I had taken a loathing to my gentleman at first sight. So had the child's family, which was only natural. But the doctor's case was what struck me. He was the usual cut and dry apothecary, of no particular age and colour, with a strong Edinburgh accent and about as emotional as a bagpipe. Well, sir, he was like the rest of us; every time he looked at my prisoner, I saw that Sawbones turn sick and white with desire to kill him. (1.8)
We get the first hint of "unnatural" circumstances early in the text.